









































































Class_ Ty 745 

Book._t J 3 _ 



COJE^lGHT DEPOSIT. 




















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V 


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First Principles 

of the 

Science of Baking 

BY 


WILLIAM JAGO, F. 1. C., F. C. S. 

of Lincoln’s Inn, Barrister-at-Law; 

Senior Examiner in Bread-making and Confectionery to the City and 
Guilds of London Institute for the Advancement of Technical 
Education; Cantor Lecturer on “Modem Developments of 
Bread-making,” and “Chemistry of Confectioners’ 

Materials and Processes,” to the Royal 
Society of Arts, London, etc. 


Co-Author of 

The Technology of Bread-Making 


) 



Chicago, Illinois, U. S. A. 
BAKERS’ HELPER COMPANY 


All rights reserved 





TX74j’ 


Copyright, 1923 

By Bakers" Helper Company 

First Printing October, 1923 


♦ 



Printed in the United States of America 


m7B’n 

I •• 

©C1A705161 


PUBLISHERS’ FOREWORD 


T his work was originally published as a series of articles 
in Bakers^ Helper, under the title “First Principles of 
the Science of Baking/^ While the series was running 
we expressed the hope that every baker among our readers 
was following it closely, as it afforded practically all the 
benefits of a correspondence course on the subject. The novel 
way in which Mr. Jago handles his theme sustains the interest 
and by its continuity of purpose renders the information 
doubly helpful. Written in easy conversational style, much in 
the manner in which the experienced baker and teacher would 
impart knowledge personally to his pupil, the text in this 
respect departs somewhat from the more formal works of the 
kind, without yielding any of the value of such'textbooks in 
accuracy, or in completeness of information as far as required 
in a book of this character. The method of presentation takes 
nothing from the excellence of the work, but widens the circle 
to whom it appeals. For the practical man who wants to 
know why he is handling his materials and the doughs into 
which he works them in a certain manner in order to get 
best results, no less than for the student who wants to learn 
these things side by side with his actual experience in the 
bread-shop, the book is recommended as a worthwhile addition 
to his working library. 

A scientist who has devoted most of his professional atten¬ 
tion to the theory and practice of flour-milling and bread¬ 
making, from the physical as well as chemical point of view, 
Mr. Jago needs no introduction as an authority to readers in 
this country any more than his own. A number of Americans 
have been among the students who have gone to work with 
him in his laboratory, and we believe that his visit to America 
in the fall of 1921 stimulated interest in his work for bakers. 
He is a shining example of the devoted worker who gives 
service regardless of whether the reward will be commensu¬ 
rate, if anything. His association with the baking industry 


is one of all-around interest, for besides being a laboratory- 
worker of profound attainments, an educator, a lawyer in 
various cases affecting bakers, and an active promoter of 
various progressive movements in the trade he has maintained 
business connection with it. In view, therefore, of his thor¬ 
ough experience of bakers and baking we, as publishers of 
Mr. Jago's works in the United States, are glad to be able 
to say sincerely that we believe it would be difficult to name 
anyone better qualified to undertake the preparation of a book 
of this kind. We offer it to the industry in the belief that 
it exemplifies the following brief quotation from the biograph¬ 
ical sketch of Mr. Jago recently written for Bakers^ Helper 
by his countryman, James Meikle: 

“Science is good for the baker, as a baker, only in so far 

as it can be made into better bread and cakes. As a baker 
he must use the science that helps him and which he can 
call to his help. Of all the bakery science I have read, I have 
the opinion that Mr. Jago’s science has been the most useful.” 


AUTHOR’S PREFACE 

T his little book is the outcome of an invitation by the 
Editor of the Bakers^ Helper to contribute a special 
series of articles to that journal. They were to deal with 
the First Principles of Bread-Making. The subject has been so 
often treated that it was difficult to find any novel method 
of la 5 dng it before the reader. After much cogitation the idea 
occurred to the author to imagine an intelligent and adequately 
educated lad who had decided to become a baker, and wished 
to be introduced to his business. It seemed a natural thing 
to take him for a tour through the bakery, point out and 
describe the various raw materials he would have to manipu¬ 
late and the different processes which finally result in the 
finished loaf of bread. Incidentally in doing this, chemical 
and other scientific explanations could be introduced in such 
a way as seemed to be called for in order to make clear the 
more practical aspect of the subject. It was hoped in this 
manner to convey the truth that science is really the handmaid 
and servant of the practical baker. It was with these aims 
that the author set out on his task. The keen interest which 
these articles have aroused leaves him to hope that he has to 
some extent at least succeeded in his object. 

And now he has been asked to arrange them for publica¬ 
tion in book-form. How should this be done? One method 
would be to remould in strictly didactic fashion, but the result, 
however correct, would probably be as dry-as-dust. As 
written, there are occasional digressions, and little interludes. 
It is well to remember the literal signification of this last 
word, ‘‘interlude”; it means a little bit of play in between. In 
teaching, which should really be a talk by teacher to student, 
these little rests serve to relieve the monotony of a too close 
application to somewhat dry subject matter, and thus help 
the student onward. They were originally introduced of set 
purpose, and are retained in the present book. The articles 
have therefore been altered as little as possible, and are re¬ 
issued in their original colloquial style. It is hoped that this 
mode of treatment will make them less difficult to read, and 
that they will prove of service to the student who is a prospec¬ 
tive baker. 

Hove, England, 

July, 1923. 


William Jago. 


CONTENTS 


Chapter Page 

I. Introductory. 9 

II. Bakers" Raw Materials, Flour, Etc. 16 

III. Bakers" Raw Materials—Continued, Yeast, Etc. .. 37 

IV. Bakers" Raw Materials—^Continued, Malt 

Products. 57 

V. Bread-Making Operations . 66 

VI. Heat, and Bread-Making Operations. 75 

VII. Temperature and Fermentation .:. 93 

VIII. Bacterial Bread-Making Troubles . 100 

IX. .Bakeshop Machinery .•.. 127 

X. Baking and Associated Heat Problems. 149 

XI. The Bakery Laboratory. 173 

Index. 187 














FIRST PRINCIPLES OF THE 
SCIENCE OF BAKING 


CHAPTER I 

INTRODUCTORY 

There is a charming little French classic entitled Autour 
de ma Chambre (Around my Bedroom), in which an invalid 
describes in detail the articles of furniture it contains and the 
mental effects they have produced on the person whose world 
is narrowed down to such small dimensions. Things that to 
the average person are but trifles become to him affairs of 
the first importance, and make appeals and have beauties, to 
which the individual in robust health is deaf and blind. Insen¬ 
sibly, perhaps, this delightful book has influenced the author 
in this attempt at a personally conducted tour of the bakery. 
Things of no importance to the ordinary man are eloquent to 
the student whose real world of work is the bakery, and in the 
following pages the attempt has been made to deal with its 
bread-making problems in that spirit. 

The very inception of this little book is an invitation from 
the Editor of the Bakers' Helper to contribute a series of 
articles to the columns of that valuable journal. In the 
letter containing this invitation there was a remark to the 
effect that each few years sees a new set of readers, to whom 
a fresh enunciation of the fundamental principled of bakery 
science would be of service. As a result, the title ‘‘First Prin¬ 
ciples" has been adopted for the present work, which consists 
of such articles moulded into what is hoped may be a more 
permanently useful form. 

Perhaps there is no time that the schoolboy looks forward 
to more ardently than that at which he will be emancipated 
from school and “begin to work." He can scarcely be regarded 
as— 

“Standing with reluctant feet 
Where the brook and river meet," 


9 



BREAD-SHOP PRACTICE 


but rather as one ready to plunge into the full river of life, 
and anxious for the attainment of complete manhood, with all 
that that term implies. Some proportion of youths at that 
happy though responsible time will have selected the trade, 
or, what one sometimes likes to call it, the Art and Craft, of 
Baking as their life occupation. It is to these young bakers 
in the embryo that the author is endeavoring to convey a 
message. 

Make the Ambitious Choice. 

One of the first sensations in the case of many thus situ¬ 
ated is that of freedom from more or less irksome lessons. 
There is no compulsion to spend the evening on home lessons, 
or what in England is called “prep’' (preparation work), but 
instead one may do what one pleases, and as a rule with more 
money in the pocket than usually falls to the lot of the average 
schoolboy. But to the young baker, as to everyone else, there 
comes a time of choice. He must either select the broad way 
or the narrow path. One does not say of the former that it 
necessarily leads to destruction; but it means at any rate 
taking the line of least resistance and one that has no ambi¬ 
tions, and at best offers only the promise of an easy time and 
mediocrity at the end of it. 

And now, how about the narrow path? What does it 
mean? It means a resolve to make one’s self the best baker 
possible, and to master every aspect of what is one of the 
noblest industries in existence. Just fancy for a moment what 
it is to provide a nation with food, and not only food, but that 
food which* has been called the staff of life. What name will 
go down to history, crowned with its wreaths and laurels, 
more illustrious than that of the American, Hoover, who 
during the late war bore like another Atlas the burden on his 
shoulders of feeding starving Belgium and the adjoining 
devastated districts of France? One therefore urges high 
aims on the young baker, and with them a renunciation of 
perhaps some of the pleasures of a life of comparative ease. 
There are many things the “best baker” has to master which 
lie outside the present author’s scope, and toward which others 
wi\] guide him, but he may at any rate try to afford some help, 


10 





BREAD-SHOP PRACTICE 


by indicating the lines of what he has called “First Principles" 
of the science of baking, and how they may best be acquired. 

Value of Self-Reliance. 

First of all, there is the principle of Self Help. It seems 
a hard saying, but there is a foundation of truth in the maxim, 
“What one is taught he never learns, but what he learns for 
himself he will never forget." Let us see what it means. 

A student at work on bread-making chemistry in a labora¬ 
tory asks his teacher the question, “What is the boiling point 
of alcohol?" The easiest thing for tne teacher is to give the 
figure at once and end the matter for himself. The student, 
however, just as easily forgets, as he has acquired, the infor¬ 
mation. Instead, the teacher may elect to reply, “There is 
the bookshelf, look the matter up for yourself"; or, “There is 
the alcohol and a thermometer, find out the boiling point your¬ 
self." Both these are courses which will fix the matter in the 
student's mind in such a way that he will be much less likely 
to forget, to say nothing of cultivating the habit of self- 
reliance. 

One sometimes hears the remark, “Learning bread-making 
science doesn't seem to make things much easier for the 
baker." Here, too, there is something of truth. It is very 
easy for a lad to watch and try to copy the work of a first-class 
workman, using solely his imitative faculty; especially if the 
workman is a good-natured fellow and will always tell him 
“the boiling point of alcohol." But is this sufficient for the 
rightly ambitious lad who wants to master his trade? Scien¬ 
tific bread-making may be at the start not so easy, on the 
contrary far more difficult; but it carries a man further and 
sets him on a higher plane of business capacity and general 
usefulness to the community. 

One ventures to hope that the preceding remarks may 
perhaps have stimulated some young bakers to take what has 
been called the narrow path, and possibly to have confiimed 
others in the same course. Some thoughts may therefore 
appropriately follow as to what constitutes First Principles 
as a matter of bakers' study. The old Latin tag experientia 
docet, experience teaches, has a value in this aspect. As a 


11 




t 


BREAD-SHOP PRACTICE 


result of his experience in a fairly long record, the writer is 
impressed by the fact that many queries have been addressed 
to him that really do not belong to the scientist’s province at 
all. When, in the endeavor to assist, a reply has been given, 
it has often happened that it actually trespassed on the domain 
of some one who could have replied much better. For instance, 
not to go beyond the list of present contributors to The 
Bakers’ Helper, we have Mr. Paul Richards and Mr. 
James Meikle, both of whom combine a thorough, knowledge 
of practice with a very keen study of science. 

There was once an enthusiastic teacher of cake-making in 
England, whose name is well known to confectioners of that 
country, who laid down his views to the writer in somewhat 
the following fashion: “Now, take Genoa Cake.” (I do not 
know if my American readers know this term, and the kind 
of cake to which it applies. I may therefore say that Genoa 
Cake is a variety of cake baked in slabs and from which a cer¬ 
tain weight is cut off and sold by the pound to each customer. 
The cake is usually composed of flour, sugar, butter and eggs, 
with or without fruit.) My friend says, “I am continually 
asked to give a recipe for a Genoa' Cake to sell at one shilling” 
(a quarter-dollar) “or other price per pound” (this, alas, was 
in pre-war days). “Now,” says he, “I do not give recipes,mor 
do I believe in so doing. What I want to do is to enable the 
inquirer to formulate his own recipe for any price and set of 
conditions. I therefore tried to explain the limitations which 
constitute a Genoa Cake; outside these the result is something 
which, whatever it is, is not Genoa in any case, or quite likely 
is not a cake at all.” Now, this is what the present writer 
calls laying down First Principles. With a knowledge of the 
limitations which govern Genoa cake, the maker can vary his 
ingredients according to price or other necessity, and can work 
out for himself a formula which will give him the best cake 
for the money he can allow it to cost him. Going a step 
further, he can modify his mode of making and baking to 
suit the variations he may introduce in his raw materials. 

How the Bakery Chemist Helps. 

Applying this law of First Principles to the making of 
bread, do not ask the scientist or chemist for a recipe for any 


12 





BREAD-SHOP PRACTICE 


particular kind of bread. That is essentially the baker’s busi¬ 
ness. But go to him for help in ascertaining the reason why 
any special step should be taken, and there science should be 
of assistance. Similarly, the chemist is not of necessity the 
best person to whom a faulty loaf should be taken for advice. 
There is many an expert baker who will detect a fault long 
before it is perceptible to the chemist; and the baker’s advice 
may most likely be of the greatest service, since, given a fault, 
his experience will suggest a remedy. But when it comes to 
the “why” of the matter, and modes of prevention that depend 
on the application of principles, then the function of science 
commences. Of course in practice these separate qualities do 
not divide themselves off into watertight compartments. The 
expert baker is now fortunately a man of considerable scien¬ 
tific attainments, while the cereal chemist is also in most cases 
a little bit of a baker. 

The writer is endeavoring to think in terms that shall be 
of help to the younger members of the coming generation of 
bakers, and must be excused when dealing with matters that 
are perfectly familiar to those who are older. So trying to 
make as much as one can out of the illustration of the faulty 
loaf, the recipe-seeking baker may get very simple and very 
efficient help for the time being by being told to alter his recipe 
by increasing the salt in his mixing by a pound, for example. 
This does very well, until another change of conditions arises, 
and then he is once more at sea, and again there must be a 
change in the recipe. This is not, by the bye, coming down 
to First Principles at all. The baker who wishes to apply 
these will ask himself why his loaf is incipiently sour. He 
will learn that sourness is a symptom of over-fermentation; 
and granted that, will ask himself what conditions accelerate 
fermentation and what retard it. He will know that salt is 
a retarding agent and hence its suggested use a moment ago. 
But he will also know that working at a lower temperature 
has a retarding action, and he will try to decide which of the 
two controlling principles it is best to invoke. Or, again, it is 
obvious that over-fermentation may be prevented by taking 
the dough earlier and thus shortening the period of fermen¬ 
tation. 


13 



• 

J 

BREAD-SHOP PRACTICE 


Wisdom of Mastering First Principles. 

But once more another set of conditions arises. Will this 
speeding up interfere with the general organization of the 
labor available? If there is some other job which will take 
half an hour to finish off, it may be very awkward to get this 
batch of dough taken half an hour before its allotted time. 

These are just a few of the questions that arise out of the 
very simple problem we have been considering, and the advice 
is a reiteration. Get a knowledge of First Principles and 
apply it. In passing, do not let it be thought that in the 
author's opinion the supplying of recipes is necessaiily a thing 
to be despised. There are many cases where a man may profit¬ 
ably avail himself of another man's solution of the problem 
rather than work out what some one else has already worked 
out. Young people, however, will often prefer to be carried 
across the stream to struggling themselves through the water; 
but those who are always carried will never learn to swim. 

The effort has been to make clear to the Younger Members 
of the trade the relation of science, or what has been called 
here First Principles, and to stimulate them to the determina¬ 
tion to study and become masters of this branch of their wx)rk. 

So far, one has been endeavoring to attract the attention 
of young bakers, and possibly also that of others, and parents 
who may wish their sons to enter the baking trade. 

Fundamental Education Important. 

First of all, one would lay it down as an absolute rule that 
a young baker requires a thoroughly sound and good pre¬ 
liminary education. This includes all that goes toward im¬ 
parting a knowledge of the underlying principles of business 
and commerce, and their application to everyday trading 
operations. Of set purpose the author leaves these matters 
to those more especially qualified to deal with them, but never¬ 
theless insists on their importance. If possible, the baker 
should know some other language than his own. To be able 
to read the scientific and technical press and literature of 
another country is a great asset in any business career. 

Coming to subjects more nearly allied to the scientific side 
of baking, one would urge some school training in the sciences 


14 





BREAD-SHOP PRACTICE 


of chemistry, physics, and biology, as being of the greatest 
value. Unless education of this t 3 rpe has been acquired before 
entering the baking trade it becomes an essential to do so 
after, and this is a tax on the energies of the young baker, 
just at the time when so many other things are demanding 
his attention. 

First Impressions. 

The baker’s apprentice, or by whatever name you call the 
learner, on first looking round the bakery or bread factory, 
will probably be struck by the stocks of raw materials he 
sees. Among these are flour, yeast, salt, shortening and 
sweetening materials, and a number of other substances. Then 
next he will take an interest in the manufacturing appliances 
that are in evidence. These will include troughs, mixing uten¬ 
sils or machines devised for making doughs, either by hand 
or by power. The ovens by which the baking of dough into 
bread or cakes is accomplished are the next item. And finally, 
there is the almost bewildering variety of kinds of bread and 
cakes that are the output of the bakery. 


15 





CHAPTER II 

BAKERS’ RAW MATERIALS 

Nature and Properties of Flour. 

Of raw materials, flour easily holds the first position be¬ 
cause of its quantity and its being the very foundation of the 
“staff of life.” Every boy knows that flour is made by grind¬ 
ing wheat, separating out the branny matter, and leaving the 
creamy-white powdered substance we call flour. But if the 
young baker looks a little more closely at the different lots of 
flour in a bakery, he will find that they are not all of the same 
character. Thus, some t 3 q)es consist of a hard, dry powder, 
while other kinds are soft and comparatively greasy to the 
touch. On inquiry, he will be told that one is a hard and the 
other a soft flour; and possibly further, that the first is a 
spring wheat, and the second a winter wheat flour. This 
possibly may be his very first initiation into varieties of flour. 
And further, he may learn that the hard or spring wheat flour 
is largely used in the manufacture of bread, while the softer 
variety is specially well adapted for the making of cakes. This 
leads to perhaps what is the first of our “First Principles”— 
the nature and properties of flom\ It is difficult here to 
decide what should be left to the textbook, and what should 
be included here. Remembering, however, that we are dis¬ 
cussing First Principles, the older baker must pardon our 
dealing with matters that are intensely familiar to him. 

Doughing Propensity of Wheat Flour. 

If our student (and that will be a shorter term than young 
baker) will only make a few experiments with the two types 
of flour, he can easily find out a lot about them for himself. 
Let him first of all take some of the hard flour and mix it 
with water in exact proportions. To do this it is well for 
him to use a pair of fairly delicate scales. Take a small cup 
or basin and balance it on the scales with anything convenient. 
Then put an ounce weight on the other side and weigh off just 
an ounce of water, next put two more ounces on and add flour 
to the extent of that weight. With a spoon or spatula mix 


16 


BREAD-SHOP PRACTICE 


the flour and water thoroughly. Notice the nature of the 
mixture, which is the substance known so well as dough. It 
is a tough and elastic mass, which properties grow more pro¬ 
nounced as the dough stands for a few minutes, and especially 
if it is worked with the fingers. Place the dough on one side. 

Next take an ounce of water and two' ounces of the soft 
flour and mix them in just the same manner. Again you get 
a dough, but even the veriest tyro notices that it is different. 
It is not so hard or stiff; neither is it so elastic, and altogether 
it is soft and sloppy compared with that from the hard wheat 
flour. Obviously, the soft flour cannot carry so much water 
for a dough of similar consistency as the hard flour; and this 
leads us to another descriptive term for the two flours. The 
hard kind is often called a strong flour, and the softer one a 
weak flour. Place this dough also aside. 

There are some two or three other experiments which the 
student may make on the same lines. Procure some oatmeal 
or rice flour, or com flour or corn meal (not cornstarch, but 
the whole flour of the com, less the branny matter). Make a 
dough from one or all of these in just the same way, but notice 
that you only get a paste which is quite devoid of the elasticity 
or India-rubber-like character of the wheaten flour dough. 
Again, procure some wood or grain alcohol (methylated 
spirit), and mix as before one ounce of this with two ounces 
of the hard flour. You simply get a paste very like that 
yielded by, say, cornmeal and water, and also without the 
elastic nature of the dough made from flour and water. 

These experiments will have taught the student several 
things about the nature of flour: First of all, that when 
mixed with water it forms the tough mass known as dough; 
secondly, that with the same proportions of flour and water, 
some flours make a much stiffer dough than others; next, 
they show that other meals or flours, such as those of rice, 
oats, and com, do not make a dough at all when mixed with 
water, but only just a non-coherent paste; and finally, that it 
is not all liquids which make a dough with wheat flour, that 
property being practically confined to water. 

Yet further experiments will throw more light on this 
doughing propensity of flour. Procure some distilled water, 


17 





BREAD-SHOP PRACTICE 


\ 

or failing that, some rain water collected in a perfectly clean 
vessel, and once more make very carefully a dough with it and 
one of the flours. Compare this dough with the dough made 
with ordinary water; and very probably, but not certainly, the 
ordinary water dough will be perceptibly the stiffer and more 
elastic of the two. Also set this dough aside. As the other 
extreme to pure water make a saturated biine, that is, a solu¬ 
tion of as much salt in water as it can be got to dissolve. 
Make a dough as before with this, and notice that it is a paste 
rather than a dough. 

Gluten, Starch and Minerals. 

We come next to something which we can do to the doughs 
which have been made. Procure a square of fine muslin, or 
the fine silk used by millers for dressing flour, and wrap the 
piece of dough up in this. Place it in a bowl of water and 
knead between the fingers; some white material oozes out, 
and gradually the dough becomes smaller and tougher. Set 
aside the first washing water, and go on washing the dough 
in fresh water until it no longer renders the water milky. 
Then open out the muslin or silk and examine the remaining 
material. It consists of a greyish mass of an elastic substance 
which is the well known gluten of the miller and baker. Com¬ 
pare the gluten of the two flours, and the yield of gluten is 
found to be much higher from the hard spring than from the 
winter flour. Further, the spring flour gluten is tougher and 
more elastic. Mould the gluten in each case into a ball, and 
dry or bake it off in a cool part of the oven. A tough, homy 
mass is the result. 

Next, take the material from the reserved washing water, 
which after a time has settled to the bottom. Pour off the 
clean water, and transferring the white material to a clean 
dish or plate dry it off very carefully. The heat of the oven 
will be too great, so it must be stood somewhere where it will 
not get above blood heat. Keep it covered over with paper, 
so that it shall not get dirty. In a day or two it will have 
become quite dry, and will be found to consist of a cake of 
friable material, readily broken down into a glistening white 
powder. This is wheat starch. In this experiment the student 


18 




BREAD-SHOP PRACTICE 


will have isolated the two constituents of flour which together 
make up from 80 to 90 per cent of absolutely dry flour. 

Taking the other flour and liquid mixtures in order, that 
of commeal and water washes away entirely if wrapped in 
muslin and kneaded in water. So, too, the paste of alcohol 
and flour washes away, leaving no gluten, if kneaded in a 
vessel of alcohol. 

The distilled water experiment gives some very interesting 
results if carefully made. Wash the dough in distilled water, 
and note that it more or less completely breaks down, leaving 
very little or no residue in the muslin. The gluten, in fact, 
disintegrates when treated with large quantities of pure 
water. One cannot at this stage explain very fully the mean¬ 
ing of this to the student. But briefly he may be told that 
flour naturally contains some mineral bodies known, as salts. 
So does ordinary drinking water. This latter may be proved 
by filling a clean basin with water and evaporating it in a 
comparatively cool part of the oven. When the moisture has 
all gone, there remains behind a thin, salt-like film. If a little 
of this be scraped off and tasted it will be found to have a 
salty flavor. The quantity of this residue varies with the 
nature and origin of the water. But little as this is, it has a 
considerable effect on the dough, and especially on the gluten 
portion thereof. The fact that flour contains certain salts 
enables it to form gluten even with distilled water, but when 
the dough is kneaded in distilled water, these salts get dis¬ 
solved or washed out and the gluten falls to pieces. The 
rapidity with which the gluten breaks down depends some¬ 
what on the amount of salts actually present in the particular 
sample of flour, which amount varies. 

An interesting modification of this experiment is to divide 
the lump of dough up into three approximately equal parts, 
and wash one only in distilled water, as previously directed. 
Then wash the second piece in ordinary water, and notice that 
it behaves quite normally and yields gluten as usual. The 
salts in the ordinary water yield sufficient binding material 
to hold the gluten together. Next take fifty ounces of dis¬ 
tilled water, which is a quart and a half-pint, and dissolve 
therein one ounce of common salt. Wash out the third por- 


19 




BREAD-SHOP PRACTICE 


tion of the dough in this salted pure water, and notice again 
that there is a yield pf normal gluten. These experiments go 
to prove that a certain amount of mineral matter is necessary 
for the proper formation of gluten. If the student consults 
with one of his seniors in the bakery he will leam that if a 
flour is very weak, and so makes a watery or sloppy dough, it 
may often be improved by using a little more salt in ordinary 
dough making. This throws an interesting sidelight on the 
effect of mineral salts on gluten. 

There now remains the mixture of flour and brine. If an 
attempt be made to wash this out in brine again there is no 
fonnation of gluten, so that too much mineral matter may also 
be injurious to the dough. 

The performance of these experiments, all of which are 
very easy, will have taught the student a good deal about the 
nature and character of his chief raw material, flour. NOTE: 
It is the personal making of the experiments, not the reading 
about them, which will really teach the student. He cannot 
help having noticed that wheat flour and water yield a sub¬ 
stance quite different in its nature from that of mixtures of 
other flours with water, or of mixtures of wheaten flour with 
other liquids. It is well to restrict this term ‘‘dough” to a 
body of the nature of wheat flour dough. We then say corn 
or rice meal will not make a dough, neither will wheat flour 
and alcohol. The character of a dough -varies materially, 
according to the quality and quantity of the gluten which the 
flour yields on mixing with water. 

This brings to a close the series of experiments, the object 
of which was to explain the nature and properties of a sub¬ 
stance called gluten, which can be extracted from wheat flour. 
In the course of those experiments a second substance, called 
starch, was also obtained as a by-product. 

What Chemistry Teaches. 

As starch may be anything from 60 to 75 per cent (in 
exceptional cases) of the whole of wheat flour it cannot be 
passed by without some specific mention. We (the student 
and the author) are here up against rather a difficulty’in the 

treatment of our subject. We have already succeeded in 
obtaining two widely different matters from flour, i. e., the 


N 


20 







BREAD-SHOP PRACTICE 


tough and elastic gluten, and the white powdery body, starch. 
This we have done by a process which the chemist calls “analy¬ 
sis,” that is, the separation of a substance into its constituent 
parts. Such operations belong to what is known as the science 
of chemistry, and we are right here in contact with the stu¬ 
dent’s duty to learn as much as possible of chemistry because 
of the help it will give him in mastering the various problems 
of science as it affects the baker. 

Let it be remembered that chemistry has been defined as 
the science which treats of the composition of matter and of 
the action and reaction which different kinds of matters have 
upon each other. In one particular kind of matter (sub¬ 
stance) we have found that in composition flour largely con¬ 
sists of two bodies, known, respectively, as gluten and starch. 
To understand fully the nature of the operation that has been 
performed, we must know something of chemistry. A good 
teacher or a good text-book will help materially at this stage; 
but all we can do in this more elementary work is to indicate 
the leading chemical points on which the student must acquire 
knowledge. 

Separation, Analysis. 

The very start is, that chemists go on separating and 
separating matter until they get a class of substances that 
cannot, by any known means, be separated into different kinds 
of matter. The bodies thus obtained are called elements, and 
the definition of these is that an element is a kind of matter 
which cannot by any known means be separated into two or 
more different kinds of matter. The elements are the bed¬ 
rock substances of nature and of chemistry. The list of them 
includes all the metals and also such substances as hydrogen, 
oxygen, chlorine, phosphorus, and other bodies known to the 
chemist. A list of these bodies will be found in any chemical 
text-book. 

Building Up, Synthesis. 

Next we come to the subject of building up, synthesis, or 
a putting together. We know that elements can combine; 
thus, if oxygen and hydrogen are mixed and a light applied, 
they combine with a violent explosion and water is the result. 


21 






BREAD-SHOP PRACTICE 


There are a number of rules which govern this act of com¬ 
bination between elements. The chief of these is that, when 
elements combine, they combine in definite proportions. Thus 
oxygen and hydrogen are both gases, and they combine to 
form water in the proportion of two volumes of hydrogen gas 
to one volume of oxygen gas. Further, the hydrogen and the 
oxygen can both be weighed, and it is then found that one 
part of hydrogen by weight combines with eight parts of 
oxygen by weight to produce nine parts of water. It is a long 
history of chemical research and investigation which has 
taught us the laws as to combination by weight and by volume. 
Summarizing the whole of this, there have now been ascer¬ 
tained, by experiments of the most delicate character, a series 
of numbers which are termed the combining weights of the 
elements. Again, a table of these, under the heading of 
Atomic or Combining Weights,’' will be found in any ordinary 
text-book of chemistry. 

Chemical Terms. 

Here a new word, “atomic,” has been introduced, which 
is an evident derivative of the word “atom.” The word itself 
is a familiar one in ordinary language, and is used to signify 
anything which is extremely small; thus it is frequently said 
that an article has been “smashed to atoms.” By the chemist, 
a yet more definite meaning is given to the word. He means 
by it what may be called the ultimate particles of matter, 
that is, particles so small that their further subdivision has 
never by any means been accomplished. These he calls atoms. 
We are not concerned with their actual size, but the smallest 
particle of the finest ground powder will contain many thou¬ 
sands of atoms. The atomic weights are the relative weights 
of these atoms, compared with each other. The lightest of 
all is that of the gas called hydrogen, and that accordingly 
has been taken as unity. Consequently, in a table of atomic 
weights, that of hydrogen is given as 1, and farther down the 
list is given that of oxygen as 16. In more modem text-books 
there is frequently a decimal number, as 15.96 for oxygen, 
but for the present the nearest whole number is more conveni¬ 
ently taken. These decimals are the results obtained by recent 
and more exact methods of determination. 


22 



BREAD-SHOP PRACTICE 


If the student pictures in his mind these atoms, then it is 
not difficult to understand that when two elements combine 
it is the atoms which combine with each other. Thus, taking 
our example of water, the chemist believes that two atoms 
of hydrogen combine with one atom of oxygen to form water; 
hence it follows that if two atoms, of hydrogen, each weighing 
1, combine with one atom of oxygen, weighing 16, the result 
is a particle of water weighing 18. This is another way of 
stating that water contains 1 part by weight of hydrogen to 
9 of water. 

A special name has been given to these compound particles 
formed by the union of atoms; they are called molecules. A 
molecule has been defined as the smallest particle of matter 
which is capable of existing alone, and which can be split up 
only into simpler molecules or atoms. 

When dealing with any new body, one of the first duties 
of the chemist is to find out its composition, and the result 
is usually expressed by him in the first place in the form of 
percentages. Thus, water consists of 89 per cent of oxygen 
and 11 per cent of hydrogen. This composition is, however, 
frequently stated in another manner, which has the advantage 
of greater clearness and simplicity. This method is based on 
having a nomenclature for atoms, and this is provided by 
calling, where possible, each element by its initial letter; or, 
where two or more elements have the same initial, using a 
combination of two letters of all after the first one. Thus 
carbon is represented by C, while chlorine is represented by 
Cl. These abbreviated names of elements are called symbols, 
and a complete list of them is given in the chemical text-books. 
But the symbol stands for more than the name, it stands for 
one atom. Further, it may be qualified by a small figure 
placed after it, indicating the number of atoms present. When 
a compound has been formed, the placing together of the sym¬ 
bols, as though they were to form one word, serves to indicate 
the compound, i. e., the composition of its molecule. As the 
comparative weights of atoms, as ascertained by analysis, 
have been embodied in tables of ''atomic weights,’’ symbols 
and formulas, together with such a table, enable us to ascer¬ 
tain exactly the composition by weight of any knowm com- 


23 







_ BREAD-SHOP PRACTICE __ 

pound. To take our one simple example of water, this may be 
written, H 2 O; and by this we mean that the molecule of water 
contains two atoms of hydrogen, each of which according to 
the table weighs 1, and one atom of oxygen, weighing 16. 

Composition of Starch and Gluten. 

After this little digression into pure chemistry we may 
come back to our starch and gluten. These both differ from 
water in that they are made up of extremely complex mole¬ 
cules. Instead of the three atoms in the water molecule, it has 
been computed that the starch molecule contains no fewer than 
4,200 atoms. Probably starch is built up of a number of 
groups of what may be called sub-molecules, which have the 
formula CisHaoOio, and there are a hundred of these sub-mole¬ 
cules in the molecule itself. Gluten consists of a mixture of 
several compounds, and of one of these it may be said that its 
simplest sub-molecule contains 646 atoms, while one cannot 
say how many of these are aggregated together to form a 
molecule. Probably the gluten bodies are even more complex 
than starch. They further differ in that they contain nitro-; 
gen and sulphur in addition to carbon, hydrogen and oxygen. 
The student should learn in passing that this group of com¬ 
pounds are called by the chemist proteins. 

What Examination of Starch Shows. 

The student may wish 'to examine further the starch he 
has separated and dried out. As already intimated, it is a 
white powder. If a little of it is taken and shaken up with 
water it forms a milky-looking fluid. Place a little of this fluid 
in a clean saucepan and heat very gently, stirring constantly. 
At a temperature of about 150 degrees Fahr. the liquid thick¬ 
ens and becomes more transparent. The starch has been gela¬ 
tinized, or converted into a jelly. When this has happened it 
is impossible to bring the starch back into its original powder 
form. 

The student who has access to a microscope can leam some¬ 
thing further by examining some of this starch with it. If a 
little of starch and water are placed under the microscope, the 
starch will be seen to consist of round or slightly oval cells. 
(The student who can obtain the instrument will know quite 


24 






BREAD-SHOP PRACTICE 



MicRoscoptc Sketches of Various Starches. 

About 4-00 diAtneters 


A.E.ruUer 


























BREAD-SHOP PRACTICE 




well how to use it for this purpose.) If a little of the gelatin¬ 
ized starch is examined in the same way, it will be found to 
have lost its cell-like shape and to consist of liquid matter^ 
with very little if any solid substance present. 

Starch is not only found in wheat, but also in many other 
vegetable bodies. Among these are included the various 
grains, as com, rice, etc., and also such substances as potatoes. 
The shape and size of the starch granules vary with the source 
of the starch, and so a microscopic examination is frequently 
employed in order to determine the origin of any particular 
sample. Incidentally, the microscope is thus used in the exam¬ 
ination of wheat flour for adulteration with com or other for¬ 
eign starches. The shape and size of some of the more import¬ 
ant starches is shown in the accompanying figure. The dimen¬ 
sions given in the figure, as for example in the case of wheat 
starch “36,” are in micromillimetres or mkm’s. This is a 
microscopic unit of measurement, being the one-thousandth 
part of a millimetre or very nearly 1/25406 inch. 

Having become a little familiar with the microscopic exam¬ 
ination of starch, the student may use this method for examin¬ 
ing more closely the act of gelatinization. If he can get a 
few test tubes let him fit them with corks. Then prepare the 
following mixtures: No. 1—1 part by weight of water to 4 
parts of wheat starch. No. 2—2 parts water to 4 of starch. 
No. 3—4 parts water to 4 of starch. No. 4—5 parts water to 
1 of starch. No. 5—20 parts water to 1 of starch. The first 
mixtures will be simply moist solids, while the latter will be 
milky fluids. Introduce samples of the different kinds sepa¬ 
rately into test tubes and cork tightly. Get a saucepan of 
water, stand all the test tubes in it and heat the saucepan. 
Shake the liquid mixtures, say every minute, uncork to relieve 
the pressure, and recork. It is not necessary to shake the 
solids, but, for the same reason, the corks should be momen¬ 
tarily removed. Continue the heating until the water is near 
the boiling point and the more watery mixtures have been 
completely gelatinized. Then remove the tubes and examine 
the contents with the microscope. The latter mixtures will 
show no signs of intact starch cells; those with only a little 
water will be but slightly altered. Some of the granules will 


26 




BREAD-SHOP PRACTICE 


be swollen and distorted, while many will be comparatively 
unchanged. From this series of tests the student learns that 
for gelatinization or cooking of starch, there must be a suffi¬ 
ciency of water. This has a bearing on the changes occurring 
during the baking of bread. In that operation only a limited 
quantity of water is present, and so complete gelatinization 
does not take place. He will, in fact, learn that a good deal 
of the starch of bread is comparatively unaltered. 

Other Constituents of Flour. 

There still remains a good deal that the student can teach 
himself about the other constituents of flour. Next, there is 
a group of bodies which are soluble in water, but in trying to 
deal with them some little general chemical knowledge must 
be assumed, or at least the possession of a text-book on the 
subject. 

Albumin. 

Take 2 ounces of flour and 10 ounces of as pure water as 
can be obtained. Place in a bottle or flask, and shake vigor- 



Filterin^ Apparatus 

ously at intervals during half an hour. After allowing it to 
stand overnight carefully pour off the upper clear liquid into 
another vessel, without disturbing the sediment. Filter this. 


27 




























BREAD-SHOP PRACTICE 


if necessary, through an ordinary paper filter. A chemical 
filter consists of a circular piece of porous “filter” paper. This 
is folded twice, then opened out into a cone, three folds of 
the paper on one side and one on the other, and then dropped 
into a glass funnel. The solution is conveniently poured down 
the side of a glass rod. See the whole arrangement in figure. 
Transfer a little of the clear liquid to a test tube and immerse 
in boiling water. As the liquid gets hot it becomes milky, and 
gradually flocks of a white substance separate out. In the 
next place, take an ordinary egg, break it, and pour a few 
drops of the white into a test tube, one third fill it with water, 
and shake up. Then immerse this also in boiling water, and 
again notice that, with heat, solid flocks separate out. What 
has happened is that the solid of the white of egg, which 
becomes hard on cooking, also becomes hard when a dilute 
mixture with water is heated. This body in the white of egg, 
which undergoes this change, is called albumin, and is one of 
the proteins. Only, unlike the proteins of gluten, it is soluble 
in water. Albumin possesses the property of coagulating on 
the application of heat. The coagulation of the clear liquid 
on being heated is due also to the presence of albumin, which 
in this case is of a vegetable origin and is called vegetable 
albumin. 

Soluble Starch. 

Other substances present in this flour solution are not rec¬ 
ognized quite so easily, but still can usually be detected. 
Probably there is a little soluble starch present, resulting from 
broken starch granules. A very convenient test for starch 
is a solution of iodine in spirit, usually called tincture of iodine. 
To a few drops of the flour solution, add a drop of iodine tinc¬ 
ture—if there is any starch present the liquid is colored an 
intense blue. 

Dextain. 

Yet another body which this solution is almost certain to 
contain is a substance called dextrin, or what is known in 
England as British gum. Dextrin is very closely allied to 
starch in its composition, and like it contains the sub-molecule 

C 12 H 20 O 10 , though in a different number to the molecule. Dex¬ 
trin is insoluble in alcohol (so also is albumin) and can be 

28 




BREAD-SHOP PRACTICE 


separated because of this property. Take some of the clear 
flour solution and heat it to boiling* point to remove albumin. 
Then filter, and to the clear solution (filtrate) add methylated 
spirit in excess, say five times the volume of the solution. A 
precipitate is thrown down, and this consists principally of 
dextrin. It may be filtered off, and then dissolved in a few 
drops of water. The solution of dextrin possesses adhesive 
properties, and two pieces of paper moistened with same may 
be stuck together. 

) Sugars in Flour. 

There are yet other important compounds present in this 
solution, and these are one or more of the sugars. Note that 
the chemist does not speak of sugar only, because there are 
several sugars which, although closely allied, are distinct 
chemical compounds. This group again is closely allied to the 
starch, inasmuch as the formula is very similar. Thus a sugar 
called maltose is usually present in the flour solution, and this 
has the formula C 12 H 22 O 11 . An inspection shows that in this 
formula there is a molecule more water, H 2 O, than in the 
starch sub-molecule. Maltose possesses the property of throw¬ 
ing down a brick-red precipitate when its solution is heated 
with what is known as Fehling’s solution. If the student has 
the facilities he may make this test. Failing it, he must take 
it for granted that the flour solution will react to this test for 
maltose sugar. He may make another experiment which may 
possibly afford some results. Place some of this flour solution 
in a basin or dish and evaporate to dryness, taking care not 
to bum the residue. Taste a little of the dry residue and 
notice that it has a more or less sweet taste. 

We have now concluded our investigations of most of the 
soluble matters contained in flour. Please remember that, 
unless otherwise stated, soluble means soluble in water. 

The Mineral Salts in Flour. 

There is just one other group of soluble matters to which 
reference must be made, and that is the mineral salts. One 
would like to indicate a method by which the student could 
isolate and recognize these for himself, but this is difficult in 
the absence of proper apparatus. Given a platinum basin, or 
even one of silica, it is not difficult, but scarcely any other 


29 





BREAD-SHOP PRACTICE 


substance answers the purpose. In any case, when flour is 
burned there is a small quantity of ash left. This is readily 
observable if the flour is heated in a platinum basin, but 
almost any other material so tarnishes that the flour residue 
is scarcely discemable. Anyway, the student may if he wishes 
place some flour in a small patty-pan, say, two to three inches 
in diameter, and heat it over a burner until all possible has 
burned away. There will remain a small quantity of a white 
ash which easily fuses into a glassy substance. This consists 
of the mineral matter of the flour. The quantity is very small, 
ranging from 0.3 per cent in the highest quality of flour to 
0.7 per cent in actually low grade. Although so little, it has 
nevertheless an important bearing on the behavior of the 
flour in relation to its other constituents. The general opinion 
of scientists now is that this small quantity of mineral matter 
has a very important effect on the strength of a particular 
flour. Another point is that the percentage of mineral matter 
is often taken as a guide to the actual grade of a flour. This 
will be readily grasped when it is realized that the highest 
grade flour, as mentioned, contains about 0.3 per cent, medium 
grades 0.4 to 0.5 per cent, and the lowest grades as much as 
0.7 per cent. 

Adds, Bases and Salts. 

In composition this mineral matter, or “ash’' as it is fre¬ 
quently termed, consists principally of potassium phosphate, 
this amounting to something like 80 to 84 per cent of the 
whole ash. Potassium phosphate is a salt of phosphoric acid 
with potash as the base. This brings us at once to the prob¬ 
lem of what the chemist means by the terms “acids, bases and 
salts.” A good many substances have what is called in com¬ 
mon parlance an acid or sour taste, as for example vinegar, or 
the juice of a lemon. Speaking generally, the. operative con¬ 
stituent of all such bodies is one of a series of chemical com¬ 
pounds which contain easily displaced (or replaceable) hydro¬ 
gen. This property is also possessed by certain compounds 
which have not a sour taste. The chemist calls these bodies 
acids, and defines them thus: “An Acid is a compound con¬ 
taining hydrogen replaceable by a metal (or compound radical) 
when offered to it’ in the form of an oxide or hydroxide; many 


30 





BREAD-SHOP PRACTICE 


acids are sour to the taste.” Taking the latter part of the 
definition first, although sourness is not an essential charac¬ 
teristic of an acid, yet it is a widely spread property of acids, 
and although certain acids are not sour it is probably correct 
to say that all sourness is due to the presence of some acid. 
This is true in such varied cases as sour apples, lemons, sour 
milk, and sour bread. 

But our definition goes further than speaking of replace¬ 
able hydrogen; it states the kind of body which effects the 
replacement, and this brings us to the definition of a base: “A 
Base is a compound, usually an oxide or hydroxide of a metal 
(or compound radical), which metal is capable of replacing the 
hydrogen of an acid when the two are placed in contact.” 

”When an acid and base react on each other, the body pro¬ 
duced by the replacement of the hydrogen of the acid by the 
metal (or compound radical) of the base is called a Salt. The 
displaced hydrogen and oxygen of the oxide or hydroxide unite 
together to form water.” 

Acids are chemically active bodies, some of course more 
than others; among their number are hydrochloric acid, sul¬ 
phuric acid, boric acid, lactic acid, etc. As the student pro¬ 
ceeds he will make acquaintance with all these. Hydrochloric 
acid may be cited as one of the stronger acids, while boric acid 
is comparatively weak. A very useful test to remember for 
acids is that they produce characteristic changes of color in 
various bodies. Among these is a vegetable extract called 
litmus, this, which is naturally blue, changing at once to red 
in the presence of free acid. The addition of certain bases 
restores the blue color. This and any other substances pos¬ 
sessing analogous properties are called indicators. Some acids 
contain only one atom of replaceable hydrogen, as for example, 
hydrochloric acid. Others, as sulphuric acid, contain two, 
while phosphoric acid contains three such atoms. Evidently 
you must get the whole or none of the hydrogen of hydrochlo¬ 
ric acid replaced by a base. But in the case of sulphuric acid 
you may get displacement in two instalments. With the one 
atom of hydrogen, what in effect is produced is a salt still 
possessing half the effective acidity of the acid itself. Such a 
salt is called an acid salt. When the whole of the hydrogen is 


31 




_ BREAD-SHOP PRACTICE __ 

thus replaced, the resultant salt is termed a normal salt. In 
the case of phosphoric acid, the hydrogen may be replaced in 
three instalments. 

Bases, again, differ very considerably in their degree of 
chemical activity. Some are comparatively inert, others are 
much more active, and among the latter are such substances 
as soda (sodium hydroxide) and potash (potassium hydrox¬ 
ide). These latter are very soluble in water and belong to a 
sub-class of bases called Alkalis. These restore very com¬ 
pletely the blue color of reddened litmus. They further possess 
the property of causing their solution to have a peculiar soapy 
feel to the fingers. 

Salts also differ according to the degree of strength or 
activity of their acids and bases. Thus sulphuric acid and 
copper oxide, a weak base, yield a salt, copper sulphate, which 
in some respects is acid in character. Carbonic acid, which 
is a weak acid, when combined with a strong base such as pot¬ 
ash yields a salt, potassium carbonate, in which the alkaline 
properties predominate. 

Investigating Properties of Acids. 

The student may very profitably investigate the properties 
of acids, etc., by a comparatively simple experiment. Procure 
some hydrochloric acid and also some sodium hydroxide (caus¬ 
tic soda). Strong hydrochloric acid is a fuming, corrosive 
liquid, and must be diluted down with, say, nine times its vol¬ 
ume of water for this experiment. Taste the diluted acid very 
carefully by placing a small quantity on the tongue by means 
of a glass rod. Notice the overwhelmingly sour taste, and at 
once rinse the mouth with a little clean water. Dissolve some 
of the caustic soda in twenty times its weight of water, and 
taste this dilute solution in the same way. It has a very dis¬ 
agreeable soapy taste. Again rinse the mouth with clean 
water. Next pour some of these diluted solutions into beakers 
or plain glass tumblers. Take some of a solution of litmus, 
and add a few drops to each. The hydrochloric acid will turn 
it a bright red, while the soda will make the blue of the litmus 
even more intense than it was originally. Next add the acid 
solution little by little to that of the soda; gradually a point is 
reached at which the blue color disappears, and a little more 


32 








i 


) 

I 

__ BREA D -SHOP PRACTICE 

acid makes the whole a bright red. Then add very carefully 
a little soda, and by degrees the color is brought to an inter¬ 
mediate purplish tint, which in England we call a port wine 
tint. But the writer must not forget that port wine is no 
longer known to the American citizen. This intermediate 
tint corresponds to the state in which there is neither free 
acid nor alkali, but only the resultant salt, in this case called 
sodium chloride. The mixed solution may next be tasted; 
sourness and soapiness have both disappeared, and instead 
there is only a distinctive saline flavor. Place this neutral 
solution in a basin and evaporate it in a warm but not too 
warm a place. A solid substance remains, which would natu¬ 
rally be white, but which is somewhat colored by the litmus 
used. Taste a little of this substance, and it will be at once 
recognized as common salt. Common salt is in fact one of the 
commonest and most plentiful of a whole group of bodies 
named salts. 

Functions of Salt in Bread-making. 

This leads us to the functions of salt in the act of bread¬ 
making. Our student in entering the bakery will not fail to 
have noticed considerable quantities of salt among the stores. 
Baking recipes contain usually about 3 pounds of salt to a 
barrel of flour (American), which runs rather higher than 
the English practice of 3 to 3^/^ pounds per sack of 280 pounds. 
This is, firstly, a flavoring agent, and if as an experiment a 
single loaf, or by accident a whole batch of bread, is made 
without salt the result is a most insipid loaf of bread. If the 
student takes counsel with an experienced baker, he will be 
told that he, the baker, has no need to wait to taste the loaf in 
order to know the salt has been forgotten. He will know it 
first of all by the exceedingly rapid fermentation—the dough 
runs away from him. The dough will be soft and runny in¬ 
stead of firm and elastic, and when baked will yield a compara¬ 
tively low, slack, and runny loaf. Salt, then, fulfills at least 
three functions in bread-making. First, it is a flavoring agent, 
next it exerts a controlling and retarding effect on fermenta¬ 
tion, and lastly it binds and toughens the dough. This latter 
property can be tested by experiment, but the weight must be 
carefully determined. The most convenient system for this 


33 







BREAD-SHOP PRACTICE 


purpose is the metric system, of which the gram is the unit 
of weight. Weigh off 196 grams of flour (miniature barrel) 
and 100 grams of water, mix thoroughly in a small basin. 
Weigh off the same quantity, and in addition thereto 3 grams 
of salt. Mix these also, and compare the respective characters 
of the resultant doughs. That containing the salt is much 
more tough and elastic. 

Fat Content of Flour. 

To revert again to our original question of the composition 
of flour, there is yet another constituent which demands pass¬ 
ing mention. That is, that flour contains a small proportion 
of fat. With laboratory apparatus this is easily separated 
and detected, but the’same is not so easy with only bakery 
facilities and appliances. Fat is practically insoluble in water, 
but is readily soluble in such substances as ether, petroleum 
spirit, and chlorofoim. In a 6-ounce bottle, place 1 ounce of 
flour and 3 ounces of either of the solvents mentioned. Shake 
up vigorously and allow to stand over night. The flour will 
have settled, and the upper liquid will have a bright yellow 
color. Shake up again, let settle and filter. Let the clear 
liquid evaporate spontaneously; at the close, place in a warm 
position and dry until all odor of the solvent has gone. There 
remains behind a small quantity of an oily or greasy sub¬ 
stance. The actual amount of this varies considerably, accord¬ 
ing to the quality of the flour. It may, however, be taken as 
roughly amounting to about 1 per cent of the flour. In view 
of the fact that the American baker uses considerable quanti¬ 
ties of edible fats or oils, about 2 per cent of the weight of his 
flour, this quantity of fat in the flour must be regarded as an 
important auxiliary to that which is added; but beyond its 
general action as a softening and enriching agent there is no 
specific importance to be attached to it. 

Summary. 

Wheat flour is the baker’s principal raw material. 

Wheat flour is of different kinds, thus some is of a hard, 
and some of a soft, nature. 

Wheat flour and w-ater, when mixed, yield a substance 


34 



BREAD-SHOP PRACTICE 


called “dough/’ which is a comparatively tough and elastic 
mass. 

Hard wheat flours make stifFer and more elastic doughs 
than do soft. 

The flours of rice, oats, and corn, when mixed with water, 
yield a paste which differs remarkably from wheat flour* 
dough. 

Wheat flour does not yield a dough when mixed with other 
liquids than water, such as alcohol. 

Wheat flour with distilled (pure) water does not usually 
make so tough a dough as when mixed with ordinary drinking 
water. 

Wheat flour will not make a proper dough if mixed with 
brine. 

When dough is washed or kneaded in water, it yields a 
tough, India-rubber-like substance called gluten, and a white 
powder called starch. 

Hard flours yield more gluten, and of a tougher character 
than do soft. 

The flours of corn, rice, etc., do not yield any gluten when 
washed in water. 

The paste of wheat flour and alcohol does not yield any 
gluten when washed in alcohol. 

The dough of wheat flour and distilled water, if washed 
in distilled water, does not yield gluten. It does yield gluten 
if washed in ordinary drinking water, or distilled water to 
which, say two per cent of salt has been added. 

The presence of mineral matter is essential to the produc¬ 
tion of gluten. 

The mixture of wheat flour and brine does not yield gluten 
^on being washed in brine. 

Wheat flour and water yield a dough possessing certain 
characteristics which are peculiar to it. The properties of 
this dough are largely governed by the quality and quantity 
of the gluten present in the flour.. 

Gluten and starch may be obtained from wheat flour by a 
process of “analysis.” 

Chemistry deals with the composition of matter. 

By continued separation, matter is reduced to elements. 


35 






BREAD-SHOP PRACTICE 


By building up, or synthesis, every chemical compound 
may be produced from the elements. 

Elements when they combine do so in definite proportions. 

Chemists regard the ultimate particles of matter as con¬ 
sisting of atoms. 

Different atoms have different weights, hence atomic 
weights. 

Atoms unite to form molecules. 

Atoms have abbreviated names called symbols, and these 
have definite comparative weights. By means of these the 
constitution and weight composition of compounds may be 
indicated. 

Composition of starch and gluten. 

Starch gelatinizes on heating with water. 

Starch granules are seen under the microscope to have 
definite sizes and shapes. 

Starch requires a sufficiency of w^ater to gelatinize. 

Certain flour bodies are soluble in water. 

Among these is vegetable albumin. 

Soluble starch is also usually present. 

Dextrin is also generally found. 

One or more of the sugars are also present in most cases. 

Flour contains certain mineral matters. The principal of 
these is a salt known as potassium phosphate. 

Nature and constitution of acids, bases, and salts. 

Common salt or sodium chloride is a typical salt. 

Salt is used as a flavoring agent in bread-making; also it 
retards the speed of feimentation and tightens up the dough. 

Flour also contains a small proportion of fatty matter. 


36 





CHAPTER III 

BAKERS’ RAW MATERIALS—Continued 

Yeast and Its Nature. 

Flour and salt having been disposed of, there remains for 
next consideration one of the most important and vital of all 
of the substances used in bread-making. That is the body 
known as Yeast. In the Dutch language, yeast becomes “gist,” 
and this comes back to us again in English, where gist as an 
English word may be defined as meaning the very essence and 
spirit of the whole thing. The student will not require to be 
told that it is due to the action of yeast that dough rises in 
the trough and the oven. There is something so mysterious 
about this change of an apparently lifeless small mass of mixed 
flour and water into a springy, resilient dough, of several 
times the size, that in older times the change was by unedu¬ 
cated people ascribed to some form of supernatural agency. 
Up to comparatively recent days, and possibly even now in 
remote districts, it was the custom of the baker on having 
made the dough to mark it, by means of a knife, with the sign 
of the Cross. The reason for this custom was unknown to 
the baker himself, and it was only by diligent inquiry that it 
was learned that the origin of the practice was a belief that 
the rising of dough was due to some demoniacal influence. The 
cross was inscribed in order to prevent the escape of the devil 
or his influence from the dough and thus to protect the sur¬ 
roundings. 

We are now so accustomed to the use of yeast that it is 
difficult to realize that its employment for bread-making was 
at first strenuously opposed. Thus in the year 1688 the Fac¬ 
ulty of Medicine of Paris gravely denounced its use as preju¬ 
dicial to the health of the people. 

Sufficient has been said to show how important a function 
yeast bears in the whole process of bread-making. Following 
the plan of this book it will be well first to desciibe the sub¬ 
stance itself, and its essential properties, and then deal with 
its active effects when discussing the actual bakehouse manu¬ 
facturing operation. 


37 


BREAD-SHOP PRACTICE 


Probably very few present students have any personal 
knowledge of yeast other than as occurring in the form of a 
moist, greyish or creamy-white solid of a soft consistency. 
This is the present manufactured form of yeast, but older 
bakers will remember the time when yeast was obtained from 
the brewery as a thick creamy liquid, or was even manufac¬ 
tured by themselves, by first of all making a preparation of 
malt and hops in water, and adding a small quantity of pre¬ 
viously made yeast to it. Soon an appearance of boiling com¬ 
menced, produced really by the rapid evolution of gas. When 
this was over, there remained a liquid possessing the general 
appearance and character of beer, and which had acquired the 
power of causing dough to rise. This liquid was known by 
the baker as “barm'' or bakers' yeast. 

Until comparatively recently the nature of the effect due 
to yeast in bread-making was very much of a mystery even 
to scientists. Thus a description of bread-making written in 
1836 states that it was a great question among chemists as 
to the nature of this barm that could produce such effects, and 
various ingenious theories were advanced, only afterwards to 
fall to the ground. “At length it was discovered that gluten 
mixed with a vegetable acid produced all the desired effects; 
and such is the nature of leaven, and such is the compound 
to which barm is indebted for its value as a panary ferment." 
There is, however, no finality about science, and the student 
of today soon realizes that much has been learned about yeast 
(or barm) since the very definite nature of the statement made 
in 1836. 

The microscope has been one of the most important agents 
in discovering the true nature of yeast, as well as the solution 
of many other scientific puzzles. As early as 1680 a Dutch¬ 
man, Leuwenhoeck, discovered by microscopic examination 
that yeast consisted of minute granules. This discovery re¬ 
mained dormant until de Latour in 1836 again called attention 
to this fact and announced that yeast consisted of little cells 
that were capable of reproduction by a process of budding. 
“Therefore," said he, “yeast must be an organism which prob¬ 
ably, by some effect of its growth, effects the decomposition 
of sugar into alcohol and carbon dioxide." This conception of 


38 



BREAD-SHOP PRACTICE 


yeast being a form of actual life instead of a dead form of 
nitrogenous matter in a particular stage of chemical change 
was a development of the most startling kind. 

This, be it remembered, was formulated’ in 1836, and from 
then onwards there was fierce controversy between the sup¬ 
porters of de Latour’s—or the vital—hypothesis, and those of 
the old school, of which Liebig was one of the chief protago¬ 
nists, who regarded yeast as a lifeless albuminous substance, 
which during its own decomposition also effected that of other 
substances, such as sugar, whose elements were only held 
together by a very feeble chemical affinity. 

Progress of Knowledge Regarding Action of Yeast. 

The next great epoch in the history of yeast was the advent 
of Pasteur, who gave the whole subject a most exhaustive 
examination, an account of which was published in book form. 
In 1857 Pasteur confirmed de Latour by the expression of his 
conviction that: 

“The chemical action of fermentation is essentially a 
correlative phenomenon of a vital act beginning and end¬ 
ing with it. I think [said he] that there is never any alco¬ 
holic fermentation without there being at the same time 
organization, development and multiplication of globules 
[of yeast], or the continued consecutive life of globules, 
already formed.” 

In 1870, Liebig admitted to all intents and purposes the 
correctness of Pasteur's views. So far as first principles are 
concerned they still hold the field, and the only point necessary 
to put on record in a work such as this is that the interior con¬ 
tents of the yeast cell are the actual agents which decompose 
sugar, and further that comparatively recently it has been 
found possible to decompose sugar by such agents even when 
completely separated from yeast cell life. Preparations of such 
constituents of yeast cells have been patented as a means of 
raising dough; though, so far as the writer knows, they have 
not met with any commercial success. 

Origin and Production of Yeast. 

With de Latour’s and Pasteur’s theory of fennentation 
before us, let us investigate the matter of yeast as it comes 


39 




BREAD-SHOP PRACTICE 


into the hands of the baker. It is evidently, although one of 
the baker’s raw materials, a finished product of some other 
manufacturer. Some little history of its origin and how it is 
made will be of service to the students. 

It is almost, if not quite, common knowledge that beer is 
made by infusing malt and hops in water and then fermenting 
the liquid by the action of yeast. The malt infusion has a 
sweet flavor, which gradually disappears during fermentation, 
while the liquid acquires a brisk taste as the result of the 
presence of carbon dioxide gas. At the same time alcohol is 
developed in it, and thus beer becomes somewhat intoxicating 
in its properties. Meanwhile an abundance of froth or scum 
rises to the surface, this consisting of the yeast which has 
been foiTued by reproduction during the act of fermentation. 
For many years this yeast, when skimmed off, was used as 
the raising agent in bread-making. 

The baker himself made a similar product, in much the 
same way, and used it also for bread-making. This was 
known as “comp.” in England (i. e., composition) or bakers’ 
home-made or “patent” yeast. 

For a good many years both of these have been practically 
supplanted by the introduction of yeast in a compressed or 
dried foim. This is a product of the spirit distiller in place 
of the brewer. As the former has no use in potable spirits 
for the bitter of hops, he uses malt and other forms of grain 
only. The bitter of hops seiwed to keep the yeast fairly pure, 
in the sense that it is an enemy to various forms of micro¬ 
scopical life, of which there are many which flourish in liquids 
of the same kind as serve for the growth of yeast. (More 
must be said about them in the future, since some of them 
are injurious to the quality of bread.) Hops not only choke 
off these deleterious organisms, but also materially reduce the 
energy and strength of yeast. Distillers’ yeast is consequently 
much more energetic than is that of the beer brewer. The 
requisite degree of purity of distillers’ yeast, in the sense of 
absence of other organisms, has to be attained by other means; 
during the course of fermentation the yeast is skimmed off 
the liquid by the distiller, after which it is washed and allowed 
to settle. A thick creamy liquid is thus obtained, which still 


40 





_ BRE A D-SHOP PRACTICE _ 

contains much, water. A good deal of this is got rid of by 
the use of centrifugal machines. 

The thick mass is next passed through filtering presses, 
and as much water as practicable is thus removed. There 
remains a comparatively dry mass, and this is packed in con¬ 
venient parcels. These in England consist of 7-pound parcels 
sewn up in jute bags. 

Proper Characteristics of Compressed Yeast. 

In the form in which compressed distillers' yeast reaches 
the bakery it should have the following characteristics: It 
should be only very slightly moist, and not sloppy to the 
touch. In color it should be a creamy white, or of only the 
faintest greyish tint. When broken, yeast should show a 
fine fracture. In taste, yeast is agreeable, and the mass 
should melt readily in the mouth. Good yeast has a pleasant 
odor, said to resemble that of apples; it should not be cheesy 
in smell, since that is an indication of staleness. Further, the 
interior of a bag of yeast should not be hot, which is a sign 
of undesirable chemical changes. 

Investigating Yeast Properties. 

The student may improve his acquaintance with yeast by 
making certain experiments which we will now describe. One 
of the first and simplest of these is the making of a dough 
with flour, yeast and water; but as this is such an everyday 
operation in the bakery it is scarcely necessary to make it as 
an experiment. The following points may, however, be noted: 
First, that a small volume of dough swells to a remarkable 
size as fermentation proceeds. Next, when a dough is at its 
fullest dimensions, make a deep cut in it with a knife and smell 
the gas which issues from the cleft. The odor is pungent and 
somewhat sweet, but nevertheless is very pleasant. These 
are in fact the characteristics of carbon dioxide gas. 

At one time compressed yeast was invariably mixed with 
starch. In small quantities this was perfectly justifiable, 
since the addition enabled the yeast to be .pressed dry much 
more easily. In larger quantities, the starch was a fraudulent 
make-weight. At present, through better methods of manu- 


41 








BREAD-SHOP PRACTICE 


facture, yeast can be properly dried without the use of any 
starch whatever, so that it may be taken as a general fact 
that yeast should contain no starch. As already stated, starch 
possesses the property of becoming intensely blue when 
treated with iodine, and this constitutes a readily applied test. 
Take a little yeast, say a piece about the size of a pea, break 
it down with some water in a test-tube and add a drop of 
iodine solution to the mixture. In the presence of starch a 
deep blue color is struck. The test may be made more sensi¬ 
tive by immersing the tube for about five minutes in boiling 
water so as to gelatinize the starch (if present), cooling, and 
then adding the iodine. With pure yeast the color is only 
the reddish yellow of the iodine. In such a'case, as a com¬ 
parative test, to the same amount of yeast add a tenth of the 
quantity of flour. Heat up and cool as before and test with 
iodine. There will at once be the blue reaction. 

Under the Microscope. 

From what has been already stated, the student will gather 
that the microscope forms a most important item in the outfit 
for the investigation of yeast. It is practically more than 
this, it is a necessity if yeast is to be readily understood. A 
fairly high power is required, viz., a sixth- or preferably an 
eighth-inch objective. To use this a certain amount of skill 
is necessary, and therefore a description of the microscope, 
and method of using it, is given because the student will con¬ 
tinually find it requisite to have recourse to this instrument 
from time to time while going on with his study of the chem¬ 
ical properties of the various constituents of bread. In order 
to thoroughly understand the physical construction of bodies 
it is necessary to see them. The microscope is an instrument 
to enable us to see points of physical construction which are 
so minute as to escape the unaided vision. The following 
description is taken from the author’s larger work on the 
Technology of Bread-Making, recently published by the 
Bakers’ Helper Company. 

.Description of Microscope. 

The demand for good microscopes has led to the supply by a 
number of makers of really excellent instruments. In conse- 


42 




BREAD-SHOP PRACTICE 


quence, the microscope is not now, even to the general public, 
an unfamiliar piece of apparatus. These pages are not the 
place where an exhaustive description of microscopes could 
with fitness be given, but as the instrument should be in the 
hands of every miller and baker, a few hints as to how to use 
it for such purposes as those occurring during milling and 
bread-making will naturally find a place in this work. 

Every reader will probably be familiar with the general 
appearance of the instrument as shown in the illustration. The 
microscope proper consists of the stand, to which is attached 
the main tube of the instrument, by means of a sliding “dove¬ 
tail” arrangement, that can be raised or lowered by a rack 
and pinion; the pair of milled heads, D, actuate this pinion. 
Below is another pair of milled heads, E, which are more deli¬ 
cate in their action, and constitute what is known as the “fine 
adjustment.” The stage, G, is that part of the instrument 
arranged for the reception of the object being examined. It 
consists of a flat surface at right angles to the axis through 
the tube of the microscope, and carries on it a pair of spring 
clips, F, by means of which the glass on which the object is 
mounted is held oni the stage, G, and thus may be shifted in 
any direction by the fingers. Underneath the stage is a con¬ 
trivance known technically as the sub-stage, H; this is also 
fitted with a rack and pinion, and may be raised or lowered 
by the milled head, I. The central aperture of the sub-stage 
is arranged to take either a sub-stage illuminator (Abbe con¬ 
denser), a series of diaphragms, the polariser of a polarising 
apparatus, or other desired sub-stage fittings. Beneath this 
again is a concave glass mirror, J, so mounted as to be easily 
placed in any required position. The tube of the microscope, 
together with the stage and mirror, can be turned at any angle 
to the tripod stand, from the vertical to the horizontal. With¬ 
in the main tube is fitted a second, B, known as the “draw 
tube,” which can be pulled out if required, thus increasing the 
distance between the eye-piece and object glass. A scale is 
engraved on the side of the draw tube, by which the amount 
of withdrawal can be observed and noted. The lower end of 
the main tube is provided with an internal screw at C, for the 
purpose of receiving the combination of lenses known as 

43 



BREAD-SHOP PRACTICE 


“object glasses/' or “objectives." The objectives of all the 
best makes are now cut with the same screw thread, and so 
are interchangeable. The “eye-piece," A, also a lens combina¬ 
tion, slides into the top of the draw tube. The objectives are 
named according to their focal length, and are consequently 
termed “1-in. objectives," etc. One of these is shown in posi- 



























BREAD-SHOP PRACTICE 


tion at L. The greater the focal length, the less is the magni¬ 
fying power of an objective. The eye-pieces also vary in 
magnifying power, and are usually referred to as 
eye-pieces, and so on; the magnification increases with each 
successive letter of the alphabet, commencing with A. The 
student will require a series of objectives, consisting of the 
2-inch, 1-inch, and 34-inch; these will be found to answer most 
purposes, although for bacteriological work a 1/12-inch oil 
immersion objective in addition is exceedingly useful. In 
working with a microscope it is frequently necessary to change 
from a high to a low magnifying power. In order to do this 
rapidly, microscopes are now provided with a carrier, K, which 
screws into the tube at C, and to which a number of objec¬ 
tives, L, LI, L2, are attached. By rotating this carrier the 
various objectives may be quickly exchanged for each other. 
In the following description it will be assumed that the instru¬ 
ment is fitted with such a carrier. For ordinary work the A 
eye-piece is sufficient, but a C eye-piece is also at times useful. 
The following accessories are requisite: one or two dozen glass 
slides, 3 inches by 1; some thin glass covers—these may be 
round or square, and should be about ^-inich diameter, or 
square; a pair of fine forceps; one or two needles set in han¬ 
dles ; a glass rod drawn out to a point at one end, and a small 
piece of glass tubing. All these may be obtained from the 
maker of the microscope, and are usually supplied in the case 
with the instrument. Other useful pieces of additiontUl appa¬ 
ratus will be mentioned as necessity arises for their employ¬ 
ment. 

A word may be said in the first place about the preserving 
of the instrument from injury. When not in use it should 
either be kept in its case, or, what is more convenient, under 
a glass shade, as then it can be readily used when required. 
A mounted longitudinal section of a grain of wheat should be 
purchased at the same time as the instrument; this is a very 
useful slide to possess, and will give the student an opportun¬ 
ity of learning how to use his microscope before he proceeds 
to mounting objects for himself. 

How to Use the Microscope. 

To commence using the instrument, remove it from the 

45 






BREAD-SHOP PRACTICE 


case, take the 2-inch obj ective out of its box and screw it into 
the bottom of the tube; next insert the eye-piece in its place. 
The lenses, if dusty, may be very gently wiped with either an 
old silk handkerchief that has been often washed, or a piece 
of wash-leather. One or other of these should be kept solely 
for this purpose. The less, however, that the lenses require 
wiping the better, as, being made of soft glass they easily 
scratch. When working on yeast, temporarily mounted in 
water or other liquid substance, it is necessary to set the stage 
horizontal, as otherwise the liquid flows downward. But with 
fixed and permanent objects, the microscope should be in¬ 
clined at an angle of about 45 degrees, as in such a position 
the eye is much less fatigued during observation. The next 
requisite is light. In the daytime choose a room that is well 
lighted, if possible not by direct sunlight, but by a bright 
cloud. At night an incandescent gas burner, especially if 
enclosed in a ground glass globe,,makes a good source of light. 
Raise the microscope tube by turning the pinion, by means of 
the milled head, D, until the end of the objective is about 2 
inches from the stage. Place the mounted wheat grain slide 
on the stage, an4 arrange the clips to hold it firmly. Next 
turn the mirror so as to throw the spot of light on the object. 
Now look down the eye-piece and lower the microscope tube 
until the object is focused; that is, until its outlines are seen 
clearly without being blurred. A word may here be said about 
the amount of light advisable; generally speaking, the rule 
may be laid down that it is wise to work with no more light 
than necessary. The light should not be bright enough to 
dazzle the eye in the slightest degree; on the other hand, it 
should be sufficient for the object to be seen comfortably. The 
2-inch objective will show the greater portion of the grain of 
wheat occupying the whole of the field of vision. Any object 
when seen through the microscope is inverted; that is, the 
top is seen at the bottom, and the left side at the right. By 
pulling out the draw tube the object is still further magnified. 

V 

In the next place rotate the carrier so as to substitute the 
1-inch for the 2-inch objective. The microscope tube will now 
have to be lowered until the object is again in focus. A smaller 


46 



BREAD-SHOP PRACTICE 


portion only of the wheat-grain is seen in the field, but that 
portion is magnified to a much greater degree. 

The illumination is much less than with the 2-inch object 

glass. Notice that more of the details of the object can be dis¬ 
tinguished. 

The 34-inch objective may now be tried. Unless the section 
is a very thin one, it will not, however, show up well. Having 
exchanged the inch for this power, lower the microscope tube 
until the end of the object glass is within an eighth of an inch 
from the slide; then move the milled head, D, very slowly and 
carefully, watching all the time until the object is again in 
focus: for this purpose, it is well to move the slide until a 
portion of the skin of the grain is in view. The milled head, 
E, may now be used for making the final adjustment of the 
focus. This latter milled head is termed the ‘‘fine adjust¬ 
ment,^^ while that by meanls of the rack and pinion is spoken 
of as the “coarse adjustment.” For the lower powers the 
coarse adjustment is sufficient. 

This exercise with the three powers will have shown the 
student the mode of using his microscope. He must accustom 
himself to moving the object about on the stage, so as to get 
any^portion he wishes in view; this presents some little diffi¬ 
culty at first, because the movement must be made in the oppo¬ 
site direction to that in) which it is desired that the magnified 
image shall travel. 

Reverting now to our microscopic examination of yeast. 
Our starting point is the appearance of the yeast itself. For 
this purpose break down a little of the yeast with water into a 
milky fluid. Place a drop of this on a microscopic slide, cover 
with a clean cover-glass, and examine. The yeast will be seen 
as an aggregation of single globules or cells of either round or 
slightly oval shape. Their dimensions can easily be measured 
with appropriate microscopic appliances, and amount roughly 
to a long diameter of one two-thousand-five-hundred-and-forti- 
eth part of an inch (1/2540 inch), with a slightly less shorter 
diameter. ‘Another way of stating this would be to say that 
2,540 such cells, placed end to end, would measure an inch. 

This experiment serves to show the inaccuracy of a term 
frequently used by bakers, who speak of “dissolving” yeast. 


47 




BREAD-SHOP PRACTICE 


When a thing is dissolved its particles do not exist as solids 
in the usual sense of the word, but enter the liquid state, and 
can no longer be detected by the microscope, nor can they be 
filtered off by any ordinary filter. When yeast is broken down 
in water the separate particles can be seen with a microscope,, 
and may be recovered by filtration. 

Beyond observing that yeast consists of a number of cells, 
let us see what else the microscope tells us about it. Careful 
examination shows that each cell has a distinct wall or envel¬ 
ope, and that the interior is filled with a somewhat fluid mass. 
This, in fact, is in consistency somewhat of the nature of a 
jelly. It is not quite homogeneous in structure, but shows 
signs of being granular. Further, the interior matter of the 
yeast cells tends to draw itself to one side of the cell, leaving 
a comparatively empty space filled only with more wateiy 
matter. The result is that a definite cavity or spot may be 
observed in the cell, which is termed a “vacuole.’' The stu¬ 
dent may amplify this experiment by repeating it on the same 
yeast day by day as it grows older; he will find that the inte¬ 
rior matter becomes more liquid and the cell wall appears thin¬ 
ner. There are other developments of this microscopic exam¬ 
ination for which the student must be referred to the more 
advanced textbooks. 


Composition) of Yeast. 

Even the elementary student may with advantage know 
something of the composition of yeast and there are just one 
or two of the simpler facts that he may learn for himself by 
performing the following experiment. Take a small porcelain 
evaporating basin about two or three inches in diameter. A 
very small saucer may be used as a makeshift. Weigh it care¬ 
fully, in gram weights if available, if not in ounce weights (for 
fractions of less than the quarter ounce, shot or other small 
fragments of lead may be used to exactly balance the basin). 
Weigh off next ten grams of yeast into the basin, or one ounce 
as the case may be. Transfer the whole to a cool part of the 
oven. The yeast will very much shrink through the evapora¬ 
tion of moisture and will probably be dry in tw^o or three hours, 
but should not be burned or seriously discolored. Weigh again 


48 





BREAD-SHOP PRACTICE 


and note the weight, after deducting that of the basin first 
determined. If ten grams were originally taken the residue 
will weigh about two grams; if an ounce, it will probably be 
less than a quarter-ounce. In other words, about 80 per cent 
of water has been driven off. 

Next put a little of the residue in a test-tube and heat 
strongly. The residue chars and emits the characteristic odor 
of burnt feathers. If a slip of red litmus paper is put in the 
issuing fumes it will be turned blue. This is a test for am¬ 
monia, and a skilled observer will recognize the odor of am¬ 
monia in the escaping fumes. The production of ammonia in 
this way is fairly conclusive evidence of the presence of nitro¬ 
genous organic matter, and from it the student is entitled to 
assume that proteins are largely present in this dry residue 
of yeast. 

The same difficulties beset the determination of ash as hold 
good \vith flour; a platinum or silica basin is almost a neces¬ 
sity. When burned off in such a vessel there is a mineral 
residue which, in fact, has almost the same composition as the 
ash of flour. The results of more accurate analyses give the 


following as about the general composition of yeast: 

PaiTs. 

Nitrogenous matter, proteins. 13 

Fat. 1 

Mineral matter, principally potassium phosphate 2 

Water . ^74 

Cellulose, etc. 10 


100 

The composition of yeast is of importance because as a 
growing body the substances of which it is composed must be 
supplied to it; this applies with special force to the proteins 
and mineral matter. 

Capabilities of Yeast. 

Next comes the study of the capabilities of yeast in the 
condition of actively performing its functions. For this pur¬ 
pose an infusion of malt such as the brewer knows as wort, 
and which on fermentation gives beer, is a very useful medium, 


49 













BREAD-SHOP PRACTICE 


since it contains sugar, and also suitable protein and mineral 
matter. The baker student can easily procure an equivalent 
for wort from the ‘^malt extract’^ used by most bakers. This 
is simply a malt wort evaporated down to a thick syrup. Take 
one ounce of malt extract, and make up to ten ounces by the 
addition of water, and when mixed you have a ten per cent 
solution of extract which answers very well for the experi¬ 
ments to be described. 

The actual modus operandi may be explained once for all. 
Take a flask which is sufficiently large and weigh it. Then 
put an additional ounce on the weight side and carefully add 
the extract until the right weight is obtained. Next put nine 
more ounces on the weight side and make up the weight with 
water. Grams may be used for this instead of ounces if the 
weights are available; as an ounce weighs 28.35 grams (avoir¬ 
dupois), the quantities taken must be arranged accordingly. 
For this experiment, 30 grams of extract may be weighed off 
and then the added weights for water would be 270 grams, 
making 300 in all, which must make a ten per cent solution, 
since the ultimate total w'eight is ten times that of the extract 
taken. Filter this solution so as to have it perfectly bright. 
Notice that it has a very sweet taste and is still of a slightly 
sirupy consistency. Place all the solution in a glass beaker or 
similar type of vessel of one and one-half pints to a quart 
capacity. Stand in warm water so as to raise to a tempera¬ 
ture of 27 degrees Centigrade or 80 degrees Fahrenheit. Take 
a fragment of yeast the size of a small pea, break it down with 
a very little of the solution, return it to the main portion and 
mix thoroughly. Stand in a warm place, such as will keep 
the temperature about the same. Notice that after a time 
bubbles of gas are being formed in the liquid and rise to the 
surface. This action becomes more and more violent, until 
shortly the whole liquid is in a state of effervescence. This is 
the appearance known as fermentation, a name which is de¬ 
rived from the Latin ferveo, I boil. After about two or three 
hours, stir up and take a small drop for microscopic examina¬ 
tion. The result should prove of great interest. There will 
probably be seen groups or clusters of yeast cells. In the 
center will be one of darker and firmer outline, while sur- 


50 



BREAD-SHOP PRACTICE 


rounding it is a number of others of more delicate character. 
The central one is the parent cell and the others are its prog¬ 
eny. These clusters of cells are usually called colonies. Fur¬ 
ther investigation will show that some of these cells have a 
much smaller one attached. Others again are cells on which 
there is a slight protuberance. In some this has grown more 
definite, and then some others may show a constriction; be¬ 
tween the two like that in the sand-filled hour-glass. With 
sufficient patience, one of the protuberances on a cell may be 
kept under constant observation, and if the whole thing is 
kept sufficiently warm, the protuberance may be seen to grow, 
and then gradually to be closed off. For a time there is a 
clear passage from the interior of one to the other, but this 
at last gets closed and an independent daughter cell has been 
formed by the process known as ^‘budding.^^ The daughter 
cell in turn evolves another bud, and so the reproduction of 
yeast goes on at a remarkably rapid rate. 

If unable to keep this patient w^atch on a single cell, the 
student can usually learn much the same lesson by seeing in 
the field of observation various cells showing all the different 
stages of development. 

Formation of Carbon Dioxide Gas. 

Let us next turn our attention to the fermenting liquid in 
the beaker. The fermentation is now at its most vigorous 
phase; there is quite a layer of froth or scum on the top, and 
this may be stirred up and mixed in with the main mass. 
Smell the gas which is being evolved so rapidly, and notice 
that it has a pungent odor, and the peculiar but easily recog¬ 
nized sweetish taste of carbon dioxide gas. Gradually, how¬ 
ever, the action; slows down, and a time is at last reached when 
the liquid becomes quite quiescent. At this stage notice first 
that the liquid has become much thinner in consistency. Then 
next taste it, the sweetness has entirely disappeared. 

Remarkable Growth of Yeast. 

After standing for, say, a day, the liquid may be filtered. 
When all possible has gone through, take the filter out of the 
funnel and lay it flat, and closed in halves, between a number 
of folds of dry calico or linen. Place a fairly heavy book 


51 




BREAD-SHOP PRACTICE 


or weight on the top and let it stand for some hours. Then 
open out and scrape the solid matter off the paper and gently 
mould into a ball. Notice that the amount of this substance 
(yeast) which is obtained is many times that of the original 
yeast which was used to start the fermentation. One thus 
learns that during fermentation yeast grows and multiplies 
to a remarkable extent. Take a little of this yeast and exam¬ 
ine it under the microscope. The colonies will most likely all 
have broken down and the yeast conisist of separate cells much 
like those with which the fermentation was started. 

Production of Alcohol. 

Next, attention may be directed to the filtered liquid or 
filtrate. If the necessary facilities are available it is well to 
make the following test: Fix up a distillation apparatus con¬ 
sisting of flask and some form of condenser. Transfer the 
liquid to the flask and boil very gently. Collect the first few 
drops from the condenser (distillate)—not more than half a 
teaspoonful—and examine it. First, smell—the liquid has a 
spirituous odor. Next, taste—the liquid has the burning taste 
of spirits. Place a light to a few drops—it bums with the well 
known flame of alcohol. All these tests go to show that dur¬ 
ing feiTnentation sugar has disappeared and carbon dioxide 
and alcohol have been produced. It is important for the baker 
to grasp the fact that the presence of sugar is necessary be¬ 
fore there can be feiTnentation. Hence the presence of sugar 
as a constituent of flour acquires a fresh interest. 

Conditions Affecting Speed of Fermentation. 

There are various conditions which affect the speed of fer¬ 
mentation, and of these the student should acquire for himself 
a certain amount of knowledge. 

First among these is the question of temperature. Pre¬ 
pare another 10 ounces of malt extract solution, but do not 
trouble to filter. Pitch as before with the addition of a small 
amount of yeast, stir thoroughly, and divide into three ap¬ 
proximately equal parts. Cool down the first to say 50 degrees 
Fahr. or 10 degrees Cent. Warm the next one to 25 degrees 
Cent, or 77 degrees Fahr., and the third to 35 degrees Cent, or 
95 degrees Fahr.; set these aside and watch the progress of 


52 





BREAD-SHOP PRACTICE 


fermentation. No. 1 will scarcely move at all unless placed 
where it can get warm. No. 2 will ferment vigorously, while 
No. 3 will absolutely race in its fermentative vigor. The con¬ 
clusion is that, at any rate within certain limits, the warmer 
the medium the more rapidly does fermentation proceed. 

Yet another experiment: Prepare a further 10 ounces of 
malt extract solution, unfiltered, raise to about 80 degrees 
Fahr., add a small amount of yeast, and stir thoroughly. Divide 
into three equal parts. Let the first one remain as made. To 
the second add 1.0 gram (say 1-30 of an ounce) of common 
salt, and stir in. To the third add 5.0 grams of salt, and stir 
in. Place all three in a moderately warm place, and watch the 
progress of fermentation. No. 1 will be the most rapid; No. 
2 will be slower, while No. 3 will ferment most slowly of all. 
Salt then has a retarding influence on fermentation. 

Yeast a Wasteful Feeder. 

The student may very well ask what is the nature of fer¬ 
mentation, and whether science can give any explanation of 
why yeast produces the remarkable changes of which a de¬ 
scription has been given. The answer has been partly antici¬ 
pated by the proof that yeast is a living organism. As sue!' 
it requires food, from which it takes what it requires for its 
own nutriment, discarding the remainder. Yeast may be 
described as a wasteful feeder. This is well illustrated by com¬ 
paring it with man. Thus, man with a body weight of about 
140 pounds requires daily about 24 ounces of dry food materi¬ 
als, which figures out very closely to 1 per cent of his weight. 
Among his articles of diet he utilizes about 95 per cent of the 
dry constituents of white bread, and about the same of meat * 
in fact, the degree of absorption hovers very closely around 
this figure for most of the normal and staple articles of diet. 
In the case of yeast, a very few globules in a few hours de¬ 
compose many times their weight of sugar and produce a rela¬ 
tively large quantity of alcohol and carbon dioxide. It has 
been estimated that the yeast utilizes about 1 per cent of the 
sugar in building up its own structure during growth and mul¬ 
tiplication, and excretes the remainder mainly as alcohol and 
carbon dioxide gas. No very clear reason has yet been given 

53 


j 







# 


BREAD-SHOP PRACTICE 


as to the cause of this apparent wastefulness of the act of 
fermentation, but one explanation is that the decomposition of 
sugar furnishes not only material for the growth and de¬ 
velopment of cells but also the heat necessary for the continu¬ 
ance of yeast life. It is this double function of sugar in fer¬ 
mentation which causes the enormous consumption of that 
compound. The fortunate part of fermentation is that 
although yeast is such a wasteful feeder the unassimilated 
products, for which yeast has no use, are of much value to 
mankind. The baker utilizes the carbon dioxide, and the spirit 
manufacturer recovers the alcohol, in their respective in¬ 
dustries. 

Composition of Sugars and Chemical Changes. 

In dealing with the constituents of flour, we have spoken 
of the sugars, and have touched on the question of their com¬ 
position. Maltose, as the sugar of malt is called, is stated to 
be one of the components of flour, and naturally is also a lead¬ 
ing component of malt extract, ’with which the preceding ex¬ 
periments have been made. Cane sugar is in many respects 
closely allied to malt sugar. Thus it has the same chemical 
formula, Cio H 22 On, but is a distinctly different substance. 

The student at this stage should grasp the principle that 
the fact of two substances each being built up of twelve atoms 
of carbon, twenty-two atoms of hydrogen and eleven atoms of 
oxygen, does not imply that they are necessarily one and the 
same substance. Take the toy known as a box of children's 
bricks or blocks as an illustration. Such a box may contain 
forty or fifty different shaped bricks. With these the child 
may build a mimic fort or a peaceful cottage. Each is radically 
different, though the number and kind of the bricks is the 
same. So in chemistry, out of the same series of atoms two or 
more very distinct compounds may be produced by building 
them up according to different plans. Cane sugar is much 
sweeter than that of malt, also it is differentiated by not pro¬ 
ducing a precipitate from Fehling’s solution. Again, there is 
a group of sugars known as glucoses, and these have the for¬ 
mula Ce Hi 2 Os. It is important to remember this because the 
modem view is that these are the only sugars capable of direct 


54 





BREAD-SHOP PRACTICE 


fermentation. Using a chemical equation as an illustration 
this is shown in the following: 

Cg Hi, Og = 2 Co Hg ho + 2 CO, 

Gluecose. Alcohol. Carbon dioxide. 

Whenever either maltose (malt sugar) or cane sugar 
(sucrose) is fermented by yeast, it is probably first changed 
into glucose. We may at once speak of at least three sugars 
which can be fermented directly or indirectly by yeast, viz., 
maltose, sucrose, and the glucoses. 

Mineral Nutriment Required by Yeast. 

Among the necessities of yeast during fermentation is an 
adequate supply of mineral nutriment. It has been already 
mentioned that the mineral matter of yeast consists principally 
of potassium phosphate and is largely identical with that of 
flour; dough itself, therefore, contains a certain amount of 
mineral nutriment for yeast.. An additional amount of phos¬ 
phate of an appropriate kind seems, however, a further food 
and acts as a decided stimulant to yeast action. Yeast pos¬ 
sesses the capacity of assimilating nitrogen from ammonia 
compounds, and therefore these bodies are also of service in 
stimulating the growth of yeast. 

Yeast AfiSnity for Free Oxygen. 

In fermentation, yeast has a very great affinity or hunger 
for free oxygen. This it satisfies in part by the absorption of 
oxygen from the air, but further obtains it by some of the 
more obscure changes it effects on sugar during its action. 
The result of this oxygenating action is to stimulate fermenta¬ 
tion generally, and thus in the case of breadmaking to cause a 
better rising of the dough. The presence in dough of any 
harmless substance which at an appropriate stage liberates free 
oxygen is therefore a decided advantage. 

Summary. 

Yeast is a most important body to the baker. Its nature 
has long been the cause of speculation. Was for many years 
regarded as a peculiar phase of dead chemical matter. 

De Latour enunciated the hypothesis that yeast is a living 


5S 





BREAD-SHOP PRACTICE 


organism, which during its growth decomposes sugar into 
alcohol and carbon dioxide. 

Pasteur confirmed this theory as the result of exhaustive 
investigation. 

Yeast is formed during the fermentation of malt wort, and 
alcohol and carbon dioxide are produced. 

Modern compressed yeast is made by the distiller. 

Characteristics of good compressed yeast. 

Observations on baking dough. 

Occurrence of starch in yeast.' 

Microscopic examination of yeast. 

Composition of yeast. 

Fermentative action of yeast on a solution of malt extract. 

Yeast multiplies by a process of budding. 

The fermenting hquid gives off carbon dioxide gas. 

When quiescent, a larger quantity of yeast may be col¬ 
lected from it than was used to start the fermentation. 

Alcohol may be obtained from the fermented liquid. 

Speed of fermentation is affected: 1st, by temperature; 
2nd, by presence of salt. 

Yeast is a wasteful feeder. It absorbs only a very small 
quantity of the sugar it decomposes. The remainder is liber¬ 
ated in forms which are of immense service to the baker and 
the spirit manufacturer. 

Composition of sugars. 

Chemical change into alcohol and carbon dioxide gas. 

Mineral nutriment of yeast. 

Yeast hunger for free oxygen. 


56 




CHAPTER IV 

BAKERS’ RAW MATERIALS—Continued 

Bakery Malt Products. 

A further investigation of the contents of the bakery 
storehouse will reveal the presence of a group of bodies of 
the nature of sugar or closely allied substances. Among these 
may be mentioned malt extract (possibly malt flour), cane 
sugar, com or rice flakes, and cooked potato flour. These 
have an important bearing on modem bread-making processes 
and therefore merit a somewhat extended description. 

Among these malt extract is one of the leading articles, 
and may be flrst described. Malt itself is made from barley 
by first moistening the grain and then allowing it to lie until 
a fairly active growth has set in. The grains each develop a 
rootlet, and this is allowed to attain a certain length. On the 
arrival of this stage the further growth of the barley is ar¬ 
rested by heating it in kilns known as malt kilns. The 
finished malt has thus nearly all its water dried out of it, 
and is consequently brittle. It has also a more or less roasted 
flavor as a result of the drying treatment. During the process 
of malting, considerable chemical changes have occurred in 
the constituents of the grain itself. The interior cell walls are 
broken down and the starch softened. The nitrogenous mat¬ 
ter, or proteins, is rendered more soluble, while a body called 
diastase is developed. The presence and effects of this sub¬ 
stance are so important that it must be described somewhat 
fully. 

Diastase and Its Functions. 

A preliminary experiment can very well be made with some 
malt flour. Heat a little com flour with water so as to form a 
moderately thick solution of gelatinized starch. Ck)ol this 
down to a temperature of about 140 degrees Fahr., and stir in 
a little malt flour. Almost instantaneously the liquid becomes 
much thinner, and if then tasted will be found to have become 
very sweet in flavor. What has happened is that the diastase of 
the malt has exerted its peculiar function of changing starch 


57 


BREAD-SHOP PRACTICE 


into maltose (and also a certain amount of dextrin). Diastase 
is one of a group of bodies, which have received the family 
name of enzymes, possessing the property of inducing chemical 
changes in certain bodies with which they are in contact. 
These changes mostly consist of causing the bodies to combine 
• with the elements of water. One of their special characteris¬ 
tics is that a minute quantity of the enzyme is capable of caus¬ 
ing the special chemical change in a comparatively enormous 
quantity of the substance acted on, without itself apparently 
undergoing change. 

Repeat this experiment with a little malt extract instead of 
malt flour; the same type of change should be produced, but 
that depends on how the malt extract has been made. This 
substance called diastase is of a nitrogenous character, and is 
very closely associated with the proteins. Also, it is soluble in 
water. Further, diastase has very little activity in the cold, 
gradually increases in energy as its solution becomes warm, 
and reaches its most active condition between 130 degrees and 
140 degrees Fahr. Above that temperature it rapidly de¬ 
clines in strength, and in solution its active converting power is 
destroyed altogether at about 180 degrees Fahr. 

Differences in Qualities of Malt Extract. 

. Some malts are more actively diastatic than others, and 
this depends largely on the amount of kiln drying to which 
they have been subjected. Very brown malts have very little 
diastase, while the paler varieties are much more active. 

The malt extract maker will choose a pale variety. In or¬ 
dinary beer brewing, the brewer warms the ground grain up 
with water and keeps it at a temperature of about 140 degrees 
Fahr. The diastase goes into solution and first of all attacks 
the starch of the malt itself, converting it into maltose and 
dextrin. In this W'ay a sweet liquid called woii; is made. Malt 
extract is simply this liquid evaporated down to the consist¬ 
ency of a syrup. But this must be done at a comparatively low 
temperature or the diastase wdll be killed. Now water and . 
other liquids boil more readily when the pressure of the air is 
removed, so the malt extract maker boils his wort down in a 
vacuum pan and thus preserves his diastase. Occasionally 


58 





BREAD-SHOP PRACTICE 


through some fault the boiling liquid gets over-hot, and so its 
diastase is weakened or even entirely destroyed. 

In order to make an extract exceptionally rich in diastase a 
cold water extract of malt is made and filtered. This contains 
most of the diastase, and no converted starch. On evaporation 
an exceptionally active diastatic extract is thus produced. 
There remains the starch of the malt in which a little diastase 
still remains. On maintaining this at 140 degrees Fahr. for 
some time the starch is converted, and from the liquid an ex¬ 
tract may be obtained very rich in maltose but deficient in 
diastase. It will readily be understood that by variations of 
these processes extracts can be produced varying from those 
which are highly diastatic down to those in which diastase is 
deficient or even entirely absent. 

One ought here to make it as plain as possible what action 
diastase really has on starch, and this may be done by means of 
the following equation: 

SCx^HsoOio + 4H,0 = Cx^H^oOxo + 4 0,2 H 22 O^x 

Starch Water Dextrin Maltose 

This really means that taking a group of five of the sub¬ 
molecules of starch, diastase causes four out of the five to com¬ 
bine each with a molecule of water to form four molecules of 
maltose. The remaining sub-molecule becomes a molecule of 
dextrin. 

Conversion of Maltose Type Sugars Into Glucose. 

There is yet a change which sugars of the maltose type may 
undergo, cane sugar comparatively readily, and maltose with 
some difficulty. This is shown in the following equation: 

CxoHooOxx + HoO = 2C6 Hx2 0c 
Cane sugar Water Glucose 

The one molecule of cane sugar assimilates a molecule of 
water, and yields two molecules of glucose. It will be remem¬ 
bered that this is the sugar which is directly fermentable by 
yeast. Although diastase is unable to convert starch further 
than maltose, malt contains another enzyme which produces 
the above change of cane sugar into glucose. This body has re¬ 
ceived the name of invertase. But the principal source of in- 
vertase is yeast, and, altogether apart from its fermentative 


59 



BREAD-SHOP PRACTICE 


power, yeast by means of its invertase secretion first produces 
the glucose from other types of sugar which afterwards it con¬ 
verts into alcohol and carbon dioxide gas. 

Action of Zymase. 

Recently, as has been already stated, the view that fer¬ 
mentation begins and ends with the activities of yeast-life 
looks as though it may have to be modified. Although one 
speaks of yeast as the essential cause of fermentation, it has 
been recognized that there must be some agent through w^hich 
it performs its functions, just as man digests his food through 
the medium of the digestive juices of the stomach. Such a 
substance has been isolated from yeast by special filtration, 
and subsequent concentration by chemical means. This body, 
in the absolute absence of yeast cells, can ferment sugar and 
maintains its activity for some days. It has received the name 
of zymase and is a member of the enzyme family. Unlike 
yeast, zymase from its very nature can have no powers of re¬ 
production. 

It is interesting to note how the chain of chemical actions 
by which starch is converted into alcohol and carbon dioxide gas 
is dependent on a series of diastatic bodies or enzymes—dias¬ 
tase, invertase, and zymase. 

This reference to the enz 3 me action of yeast does not upset 
the correctness of Pasteur’s theory of fermentation as a 
working hypothesis, since in practice it is only by very special 
and recently discovered means that zymase can be separated 
from the yeast. When working with yeast the zymase does 
not get separated, and so under ordinary conditions fermenta¬ 
tion ends with the destruction of the yeast cell. 

Function of Cane Sugar in Bread Making. 

In the group of bakery stores, we followed malt extract by 
the mention of cane sugar. This is used in bread as a sw’eet- 
ening agent and also as a yeast food, since it is readily changed 
into glucose, and so supports fermentation. It has, however, 
no diastatic properties. In sufficient quantity, cane sugar 
materially affects the character of flour in a dough; but while 
this has considerable importance in the study of cake-making, 


60 






BREAD-SHOP PRACTICE 


the amount used in the manufacture of bread is not enough to 
cause any great change. 

Properties of Com Flakes and Cooked Potato. 

Yet other members of the same group were com or rice 
flakes and cooked potato flour. Of these the two first named 
consist of the hulled grain, subjected to a cooking process by 
the action of hot water or steam, and then passed through a 
pair of hot rolls by which the kernel is flattened to a flake and 
at the same time dried. Such flakes, themselves, in a dough 
give moistness to the resultant bread. If used together with 
malt flour or malt extract, more or less diastatic action ensues 
and dextrin and maltose are produced in the dough. Cooked 
potato flour is made on the same lines. The potatoes are first 
cooked, then carefully dried, and finally reduced to flour. The 
whole potato contains about 75 per cent of water, while the 
dried potato has the following approximate composition: 


Starch. 62 

Proteins. 14 

Dextrin. 5 

Sugar. 4 

Fat. 1 

Extractive matter. 6 

Cellulose. 4 

Ash. 4 


100 

The composition is not unlike that of wheaten flour, but as a 
result of the cooking all the starch is in the gelatinized form. 

In the presence of malt extract this also becomes to a cer¬ 
tain extent changed in the dough to maltose and dextrin. The 
other ingredients have, however, a very decided influence in 
bread-making, since they act as energetic yeast stimulants. In 
early days, when brewer’s yeast was almost universally used, 
potatoes were largely employed as a food and stimulant for the 
yeast itself. Cooked potato preparations, such as are being 
described, serve the same purpose without entailing the addi¬ 
tional labor and inconvenience of daily cooking large quantities 
of potatoes in a bakery. 

61 


i 














BREAD-SHOP PRACTICE 


Fatty Ingredients of Bread. 

The bread-making stores include also various fats in con¬ 
siderable quantities. These comprise substances such as but¬ 
ter, possibly margarine, lard, and cottonseed oil preparations. 
If price were no object, butter would easily displace all other 
forms of fat in most bakeries. But England, when these words 
were first written, showed no bakeries where butter could be 
used in bread-making; the difficulty was in fact to get butter to 
put on it when the rationed allowance was 1 ounce per head per 
week. Margarine has largely become a substitute in England 
for butter. But probably for bread-making purposes, Ameri¬ 
can bakers now use principally lard or cottonseed oil products. 
A description of their origin is scarcely necessary, since it is 
generally known that lard is the refined fat of the pig, while 
the oil of the cottonseed on being purified is used either alone 
or in mixture with hardening animal fats as a fatty ingredient 
of bread. 

It may be of interest to place on record here that extra 
sugar and fat are rarely used in English methods of making 
bread, whereas in America a considerable proportion of each 
is employed. Fat is largely a flavoring agent, and fats as a 
whole confer a softness and mellowmess of flavor that is ex¬ 
ceedingly palatable. Further, the specific fiavor of such a deli¬ 
cate fat as butter enhances that of the bread in ' which it is 
used. 

Fat is also knowm as ‘‘shortening,” and it has the effect of 
causing the crust of bread to be short and brittle instead of soft 
and tough. Fat is one of those moistening agents which more 
or less wet up the flour without the production of gluten, and 
so may make dough shorter by actually inhibiting the forma¬ 
tion of gluten. This is well illustrated by the Scotch short¬ 
bread, in which butter is the only moistening agent; there is 
no gluten in such a dough. Fats, however, in ordinary bread 
dough operate probably by inteiposing a greasy film between 
the particles of the dough and thus reduce its tenacity. Fats 
are asserted to deaden fermentation. The writer does not 
know of any poisonous or toxic action they have on yeast, but 
probably their presence more or less shields the particles of 
sugar from the yeast. Further, if fat lessens the tenacity of 


62 





BREAD-SHOP PRACTICE 


the dough it will not rise and produce so bold a loaf, therefore, 
in this secondary fashion, fat may impair the efficiency of the 
yeast in bread-making. 

Moistening Ingredients of Bread. 

The whole of the essentials of bread-making stores have 
now been dealt with. There remain the moistening ingredi¬ 
ents. These include in the first place water, and secondly the 
limited use of milk. As a rule the baker has to be content with 
the water supplied to him by the governing authority of the 
district in which his bakery is situated. Such authorities take 
a serious view of their responsibilities, so usually such water is 
perfectly pure and wholesome. If the baker has to procure his 
own supply it behooves him to see that it is pure; above all, 
it must be free from sewage contamination. For this purpose 
he should call in the assistance of a local analyst who is com¬ 
petent to advise him as to the water supply. Apart from or¬ 
ganic purity, the presence of a certain amount of salts is rather 
an advantage to the baker. Some of these have a hardening 
and toughening action on the flour, while carbonates (such as 
that of lime) in solution neutralize some of the acidity that 
may be produced during bread-making. Everything else being 
equal, a rather hard water is generally to be preferred by the 
baker to a very soft one. 

Milk as a Moistening Agent. 

In the better and more expensive kinds of bread, milk to a 
certain extent replaces water as a moistening agent. The fol¬ 
lowing is given as the average composition of pure cow’s milk: 


Fat. 4.0 

Proteins . 3.6 

Sugar, lactose. 4.5 

Ash. 0.7 

Total non-fatty solids. 8.8 

Water. 87.2 


100.0 

Milk, then, is roughly seven-eighths water and one-eighth 
milk solids. Again, roughly, after allowing 0.7 per cent ash. 




63 










BREAD-SHOP PRACTICE 


the remaining 12 per cent may be regarded as consisting of fat, 
proteins, and sugar in equal parts. Obviously the water of 
milk has just the same action in bread-making as water from 
any other source. Of the solid ingredients, the fat is identical 
with that of butter, while the proteins constitute those of 
cheese. The sugar is known as lactose or sugar of milk; it has 
the same formula, C 12 Hoo On, as sucrose and maltose, but it is 
a perfectly distinct sugar. For one thing, it is not so sweet as 
the other two sugars; for another, it is not fermentable and so 
is unacted on by yeast. When milk wholly or partly substi¬ 
tutes water in bread-making its fat operates as a shortening 
and enriching agent. The proteins would seem to be a correc¬ 
tive of harshness, as they have a bland effect on the bread. 
The sugar slightly sweetens, and the whole combination im¬ 
parts the delicate and pleasant flavor of the milk itself. 

Milk Powder. 

Milk powder is at times used as a substitute for milk. It 
consists of the dried residue resulting from the evaporation of 
milk. In its preparation, milk is injected as a fine spray into 
a hot air chamber, the water is evaporated, and the solids are 
collected as a dry powder. Its composition may be taken as 
that given above for the solids of milk. There are three 
definite grades of milk powder supplied, viz.: Full-cream milk 
(composition as above), half cream milk, and skim or separ¬ 
ated milk. The buyer must evidently be on the alert as to 
which he is receiving, since the fat is far the most expensive 
of the constituents. One part of full cream milk powder is the 
equivalent of eight parts of fresh pure milk, and one forms a 
fair substitute for the other. Assuming that both fresh milk 
and full cream powder are unsophisticated, the weight cost of 
the latter should not be more than eight times that of the 
former to give an average economic equivalent. But while 
fresh milk must be had in daily, and even then may turn sour, 
milk powder keeps well for some months and so is a dependable 
standby in the case of shortage of milk. This is a factor which 
may fairly be taken into account in reckoning the comparative 
values of fresh milk and milk powder. 

The preceding has been a fairly comprehensive description 
of the raw materials which may be found in the modern 


64 




I 


_ BREA D- SHOP PRACTICE _ 

bakers’ store rooms. A knowledge of these will greatly help 
the student when he comes to employ them in the manufactur¬ 
ing operations of bread-making. 

Suimnary. 

Detailed description of bakery malt products. 

Diastatic properties of malt. 

Diastase and the enzymes. 

Varieties and qualities of malt extract. 

Diastase, in the presence of water, changes starch into 
dextrin and maltose. 

Cane sugar and maltose are converted by the assimilation 
• of water into glucose. 

Yeast contains an enzyme called zymase, by which is ef¬ 
fected conversion of glucose into alcohol and carbon dioxide. 

There is thus a chain of enzymes upon which is dependent 
the whole series of changes by which the conversion of starch 
into alcohol and carbon dioxide is produced. 

Cane sugar and its functions in bread-making. 

Properties of com flakes and cooked potato. 

Effect of these bodies on malt extract. 

Fats, butter, lard, and cottonseed oil products. 

Water as a moistening agent. Necessity for purity. Effect 
' of hardness. 

Milk as a moistening agent. Composition. Milk powder as 
a substitute for milk. 



65 





CHAPTER V 

BREAD-MAKING OPERATIONS 

Blending of Flours. 

Our next stage is to try to see our friend and student 
through the work of the bakery. There is no important 
amount of preliminary treatment of raw materials except 
perhaps that of blending flour. It has already been made 
clear that flours may be divided into hard and soft, colory 
and non-colory (respectively white and dark flours), and flavory 
and non-flavory (i. e., those in which good flavor is very pro¬ 
nounced or else comparatively absent). Over and above all 
these is the question of cost. In consideration of the selling 
price of bread, the baker has to determine how much he can 
afford to pay for his flour. The whole question of costings lies 
outside the scope of the present book, but as a general rule it 
may be laid down that flour should be purchased up to the 
limit of price that commercial considerations justify. Always 
a good article is good policy. With this view ever before us, 
the question of blend is one that each baker must decide for 
himself. To start with, he must know the wishes, likes, dis¬ 
likes, and even prejudices of his customers. In one district 
they may like a creamy white loaf and are prepared to sacri¬ 
fice almost anything else to that. In another, wh^t they want 
is sweetness of flavor, in yet another a bold, full-volumed loaf. 
All these must influence the problem of blend. What can be 
done? 

An observant baker 'will study what is being done by his 
more successful competitors. Further, he 'will note the nature 
of the complaints made by his own customers, and see if they 
give him any guide to what the public requirements really 
are. (Very frequently they do not.) Anyway, first of all 
gauge as accurately as possible what the consumer actually 
wants. Educate her or him up to higher standards if you 
'will, but never forget that the baker is after all but the servant 
of the public. It is no good telling the public that yours is a 
long way better and nicer loaf than that they have been used 


66 


_ BREAD-SHOP PRACTICE _ 

to. If they prefer something else you have just got to supply 
it, or else take a back seat and let somebody else do the busi¬ 
ness. 

Here in England one can point to towns within forty miles 
of each other where diametrically opposite kinds of bread are 
the custom, and where the bread of one could not be sucess- 
fully introduced in the other. This being so, how much greater 
must be the variations in America, with its greater distances 
and less homogeneity of population! All this brings us back 
to the general proposition—know the requirements of your 
own immediate prospective customers and then supply the 
article which best meets those requirements. 

Making Baking Tests. 

How can these best be ascertained ? Something in the way 
of an answer has been somewhat anticipated in the foregoing 
remarks. But to condescend to details, the careful baker will 
have made a number of experimental loaves from the various 
flours in his possession, noting their respective characteristics 
in each case. From this, he will proceed to make a blend, 
taking so many parts of each, thoroughly mixing them, and 
then making a loaf. This he will judge very critically in the 
way of those qualities he thinks his customers will appreciate. 
The loaf may be deficient in sweetness or some other quality; 
then his next object is to prepare a fresh blend, using more 
of the flour which possesses the desiderated characteristics. 
Again this is baked, and a judgment formed as to its suit¬ 
ability. This process has to be repeated until the (nearly as 
possible) perfect loaf has been obtained. 

Then the question of cost arises. That of the mixture is 
easily calculated from that of the quantities and individual 
price of each constituent. In pricing out the bread, regard 
must be had to the water-absorbing and yielding capacity of 
the blend. Obviously the mixture must allow a margin that 
is in cost safe commercially. 

The next thing is how to gauge how far the public will 
appreciate the proposed bread. One does not wish to speak 
too definitely on this point, but one may put on record the 
practice of one shrewd old baker. He had picked out some 


67 





BREAD-SHOP PRACTICE 


half dozen customers on whose critical judgment he could 
rely. Then when a change was made, or any new development 
was in prospect, trial loaves were submitted to these, and 
their opinion requested. The result was as a rule successful 
and served to guide him in his selection of blends, etc., for 
carrying on his business. This may seem perhaps too prolix 
for usual practice, but, of course, every baker has first of all 
to decide on his general methods. When he has settled down 
to these, the matter of arranging his blends of flour so far as 
substituting one flour for another does not call for so much 
experimental research. 

Modes of Blending. 

Having decided on what is the best mixture to use, the 
next step is that of blending. When hand labor was the only 
available method, the various flours in the desired propor¬ 
tions could be emptied out in a mixing room, and then turned 
over with a spade until thoroughly blended. With more 
modem appliances there are machine-mixing arrangements 
which really do all that is necessary. It should be borne in 
mind, in deciding as to proportions of blend, that the flour 
is already weighed off into barrel quantities, so that these 
are conveniently taken as the units of the mixing proportions. 
The preceding arrangements are those which hold in the larger 
bakeries; in the very small ones, the various flours are w^eighed 
out in their respective proportions and discharged into the 
dough trough, after which they are mixed by hand. 

How Science Helps in Actual Bakeiy Operations. 

Having acquired some knowledge of the scientific aspects 
of the bakers’ raw materials, our student will now wish, and 
quite naturally, to feel how far science helps him in actual 
bakery operations. Let us assume that all is in readiness and 
that a dough is about to be made. In a hand bakery the flour 
is weighed off into the mixing trough. The fat is weighed off, 
warmed a little so as to soften, and rubbed into the flour. The 
salt may also be mixed in the flour. These mixed ingredients 
are drawn to one side of the trough so as to allow a space for 
the water or other moistening constituents. The yeast is 
weighed off and broken down in a portion of the doughing 


68 





BREAD-SHOP PRACTICE 


water. Any sweetening agent, as sugar or malt extract, may 
be dissolved in another portion of the water. These are both 
mixed in with the bulk of such water, and poured into the 
vacant part of the trough. 

In such mixing, do not make the mistake w'hich the writer 
committed at a time when he ought to (and as a matter of 
fact did) know better. He had arranged for the introduction 
of all other ingredients, and then taken a pail of water and 
dissolved the salt in it. In the same lot of water, he broke 
down the yeast, which evidently was thus at the start pickled 
in a strong brine before mixed in the dough. It will surprise 
no one to learn that that dough never made a decent loaf of 
bread. For such reasons the yeast and salt must be broken 
down in different, lots of water so as to prevent their meeting 
one another in concentrated form. It is not at all a bad plan 
to rub the salt into the flour. 

The liquor being in the trough, the flour is pulled over 
into it, and gradually but thoroughly mixed in. This is a long 
and arduous occupation and literally fulfills the slightly modi¬ 
fied injunction: ‘‘By the sweat of the baker’s face, shall the 
people eat bread.” 

Machinery Alleviates Hard Work. 

In modem bakeries this is greatly alleviated by the intro¬ 
duction of machinery. Perhaps the author has some personal 
prejudices in the matter, but if there is one thing which he 
hates, it is to see a man doing donkey-work. Surely a man is 
too fine a product of creative power to be used simply in order 
to avail one’s self of his brute strength. For such reasons, he 
welcomes the relief of the baker by the use of mechanical mix¬ 
ing appliances. Essentially all these consist of a mixing 
trough, and an arm or arms actuated by mechanical power, 
by which the mixing is effected. 

Changes Required for Machine Mixing. 

Some little alteration of the order of introducing ingredi¬ 
ents is advisable with such a machine. Usually the water, 
with sugar, yeast, and possibly salt, is first introduced in the 
machine. Then next the flour with already incorporated fat is 
gradually added, the machine being in motion all the time, until 


69 






BREAD-SHOP PRACTICE • 


a thoroughly mixed dough of the proper consistency has been 
made. This is the simplest method of making a dough 
employed by the baker, and is usually known as a ‘^straight 
doiigh.” It should be noticed that the^flour is in these cases 
gradually worked into the water. The reason is that when an 
excess of water forms a slack dough more flour is readily 
worked into it. But if one starts with an excess of flour and 
thus makes a very stiff dough, water is only worked into it 
with great difficulty. And if the operation be carefully 
watched, there will be noticed a slight separation of the dough 
into starch and gluten. This does not favor absolute homo¬ 
geneity of the dough. In modem doughing machines of high 
efficiency the materials are, however, ultimately, and usually, 
thoroughly mixed, and consequently many .operatives do not 
trouble greatly as to the order of adding ingredients. 

Space does not permit elaboration of all the considerations 
which enter this problem. For example, there is the very 
simple one of the trough of the machine being so leaky that 
if the water is added first a good deal of it runs out, while if 
the flour is added it serves to stop up and staunch the leaks. 
Obviously leakiness of this kind is a great fault of a machine, 
and certainly the repairs ought not to be made with the dough 
intended for bread. One must not dogmatize too severely on 
these matters, since with machines of different types the 
mechanical operation of mixing does not take place in quite 
the same way. As a matter of fact, all the ingredients may 
be added in some machines, which when started up succeed 
in incorporating them fairly evenly at the start, and before 
a stiff dough, with water afterwards to work into it, has been 
formed. It is this latter condition which one wants to avoid 
for the reasons previously given. Whatever the nature of the 
machinery, the writer has always regarded as the ideal ar¬ 
rangement that in which the liquid ingredients are first intro¬ 
duced into the trough of the machine, and the mixing blades 
set in motion, after which the flour is passed through a sift¬ 
ing machine, which thus at the last moment removes any 
traces of foreign matter accidentally present and thoroughly 
aerates the flour, which drops in a fine stream into the liquid 
constituents already in the trough. 


70 






BREAD-SHOP PRACTICE 


Avoid Over-Mixing. 

A question which is frequently asked is “Can a dough be 
mixed too much ?” And the answer must be in the affirmative. 
This problem did not arise in the old hand-made dough days, 
since when the baker did all the hard manual work of mixing 
himself he wasted no extra energy in overdoing the mixing. 
With the machine it is different—^while one batch is being 
kneaded the operator is generally measuring and getting ready 
his quantities for the next. And it is very easy to let the 
machine go on grinding away while the measuring out is being 
done. 

Rule of Machine Dough Kneading. 

How does one know when the mixing is sufficiently ad¬ 
vanced ? First of all the dough should be of even stiffness all 
over; that is, there should not be one portion slack and another 
over-stiff. The flour should all be worked in, but only just 
worked in. The writer has seen highly skilled bakers at work 
who did not hesitate to turn out the dough when particles of 
less-wetted flour could on close inspection be seen disseminated 
through‘the mass of dough. On being questioned the reply 
would be that all these would be absorbed in the dough and 
disappear in a very few minutes’ time. Every baker gets to 
know the idiosyncracies of his own machine (or shall I say its 
whims?), and so ought to gauge just exactly the amount of 
kneading that is sufficient. The golden rule is, “Give the least 
amount of kneading possible that will result in an even, 
smooth dough.” ♦ 

Effect of Over-Kneading on Bread. 

It may be asked, what happens if the dough is over¬ 
kneaded? The older baker will tell you that “it kills or fells 
the dough” and makes it lifeless and putty-like; further, that 
a close, heavy loaf is the result. In this he is substantially 
correct. There is a very interesting experiment that can be 
made in illustration of this. Certain firms make miniature 
dough mixing machines for tests on flour. These will operate 
on as little as 11/2 ounces of flour. With one of these avail- ' 
able, take sufficient well washed wet gluten to fill the machine 
to its kneading point, start kneading the gluten and continue 


71 




BREAD-SHOP PRACTICE 


for a considerable time. Periodically examine the condition of 
the gluten. It will be found to lose its rubber-like elasticity 
and become soft and sticky. Gradually it will be reduced to 
a consistency more like that of bird-lime. The elasticity, 
therefore, of wet gluten itself may be destroyed by the physi¬ 
cal operation of over-kneading, and in this way the dough is 
injured. The gluten of soft flours is more delicate in that 
direction than that of hard, and so when, for the sake of flavor, 
a somewhat high proportion of soft flour is used in the blend, 
there is all the more danger of injury from over-kneading. 
The machine baker sometimes remedies this by using a larger 
proportion of strong flour; but the result is that the flavor of 
his bread suffers. This is one of the causes why machine-made 
bread is often said to be harsher and more flavorless than 
hand-made. The remedy is, avoid over machine-kneading and 
treat the dough as gently as possible in it. 

Modern High Speed Kneading Machines. 

Since the above was written, there have been certain very 

interesting developments in modern American kneading ma¬ 
chines. Certain very successful machines have been made in 

which the dough is operated on by beating arms which revolve 
at a very high rate of speed. These arms or blades are made 
.hollow, and have pure, cooled and washed air forced through 
them during the kneading. The amount of work done on the 
dough is far in excess of what was formerly thought advis¬ 
able, and produces favorable results. The dough most suited 
to the machine is that of the slack type, and this with the 
more modern practice of using yeast in full quantity produces 
a dough to which the previously mentioned criticisms do not 
apply. A careful examination of the dough shows that the 
gluten acquires to a certain extent the soft consistency above 
referred to; but this is held in control probably by the vigor¬ 
ous aeration which takes place. The consequence is that the 
dough produces a loaf of good appearance and remarkably 
silky texture. 

Evolution of Bread Making Recipes. 

As making dough is the very foundation of all the opera¬ 
tions of breadmaking, it has been dealt with pretty fully, and 


72 





BREAD-SHOP PRACTICE 


some of my student-readers may say that not a single point 
has been given as to quantities of materials. For this there 
are definite reasons, one of which is that a recipe which suits 
one baker and district will not suit another, and there is no 
such thing as an absolute best recipe since what would be 
best in one locality would not be the best in another. Further, 
the actual recipes of bakers for a district are usually available, 
and it may be taken for granted that in its broad outline the 
accumulated experience of all the bakers of a community will 
have evolved a sound working rule that in the main meets the 
requirements of the consumer. This rule does not preclude 
the ambitious man from trying to be:ter the achievements of 
his predecessors, and the author will endeavor to indicate the 
lines on which this may be done as he proceeds. But to be of 
any great good the experimental work of it must be done by 
the baker himself. 

When dealing with the problem of making a flour blend, the 
principles underlying such investigations were explained, and 
much the same methods apply to possible improvements in the 
formula or recipe. If the bread requires to be made better, de¬ 
cide first of all in what particular direction the improvement 
is needed. Maybe it lacks sweetness or moistness or the crust 
is too tough, or there may be other faults positive or negative. 
Then, next of all, one must inquire of one’s self, is the fault due 
to my ingredients or to my mode of using them ? If the answer 
points to the ingredients the next problem is what alteration 
to make. The desciiptions already given of the constituents 
of a loaf of bread will be a help in deciding what these altera¬ 
tions are. Thus lack of sweetness may point to an increase in 
the quantity of sugar or malt extract. Experiments may be 
made with different proportions, and the results carefully com¬ 
pared until any desired improvement is effected. Then the 
work of costing comes in, and it must be decided what degree 
of good quality the price of that particular loaf will bear. 

Intimate Relation of Formula and Process. 

It may be that the baker will incline to the view that it is 
his processes rather than his raw materials that are at fault. In 
that case his remedies belong rather to the portion of our work 


73 




BREAD-SHOP PRACTICE 


which still lies before us. One word of warning may be given. 
The proportions of materials used in a bread formula are so 
intimately bound up with the whole process of making, that 
an alteration of the one, without adequate provision of 
changes in the other, may result in disastrous consequences 
to the general quality of the loaf. 

Summary. 

Blending of flour. Principles of selection, guides to same. 
Modes of blending. 

Dough-making procedure in a hand bakery. 

Yeast must not be broken down in a strong salt solution. 
* Machinery alleviates the hard work of making dough by 
hand. 

Flour should be worked into water, and not water into a 
stiff dough. 

Flour should be sifted into the mixed liquid ingredients in 
the case of machine-made dough. 

Over-kneading of dough, not likely by hand, may occur 
with machine. 

Rule of machine dough-kneading. 

Results of over-kneading. Effect on blend. 

Evolution of bread-making recipes. 

Intimate relation of bread-making formula and manufao 
turing processes. 


74 



CHAPTER VI 

HEAT AND BREAD-MAKING OPERATIONS 

Warmth of Doughing Water, * 

There is one vital consideration which underlies the whole 
question of dough-making of which no mention whatever has 
been made, and the writer rather wonders whether the student 
will have “spotted^^ the omission. The matter is of such impor¬ 
tance that it has purposely been reserved for full treatment 
at an appropriate stage, and that has now been reached. The 
baker student will have noticed in his work in the bakery that 
the warmth of the water used in making dough has been 
carefully studied and adjusted. This is necessary because the 
proper degree of warmth governs the whole process of fer¬ 
mentation. And what is actually wanted is the proper warmth 
of the made dough, and its maintenance at that point during 
the whole period until it reaches the oven. 

And now, how is it best to tackle this question? Probably 
the simplest course is to explain first the scientific principles 
which underlie this matter of warmth, and the modes of ap¬ 
preciating and measuring the same. We all of us know what 
is conveyed by the phrase: “How hot it is,” or the companion 
one, “How cold it is.” This brings us to the first elemental 
principle of heat and cold. Now primarily warmth is a sen¬ 
sation. We say that a body feels cold, warm, or hot. Our 
starting point is that what we call heat produces certain 
definite effects on our feelings as human beings. But there 
are other well, or even better, defined effects which heat pro¬ 
duces. As a body gets warm and then hot to the touch, cer¬ 
tain other changes occur, the volume of the body as a rule in¬ 
creases, then with still more heat a solid body will melt, as 
for instance butter or other solid fat. Then in the case of 
liquids, as water for instance, as they are made hotter a point 
is reached at which they boil or are converted into gas, disap¬ 
pearing entirely as liquids. Then if you commence to cool such 
a substance as steam, it becomes water, and if further cooled 
freezes or is converted into a solid. 


75 


BREAD-SHOP PRACTICE 


Heat Has No Weight. 

Now all these changes which may occur first in making a 
body hot, and next in making it cold, are characterized by one 
important property, there is no variation in weight. If you 
subject a thing to the action of heat, for example a bar of iron 
which you put in the fire, it acquires something which makes 
it red-hot, .but that acquirement does not make it any heavier. 
When you take it out it gradually cools, and if held to the face 
it gives something to the face because the latter feels warm 
and gets warm. Still, with all this, the bar of iron in cooling 
does not get any lighter. 

Heat, therefore, is something which may be passed from 
body to body and yet does not possess weight. The scientist 
looks upon heat as a form of force and regards it as a mode or 
variety of internal motion of the particles of bodies—the 
hotter they are, the more violent and energetic is the motion. 

Temperature the Measure of Warmth. 

The measure of this property of warmth is teraied tem¬ 
perature, which may be shortly defined in the following man¬ 
ner: “The temperature of a body is a measure of the intensity 
of its heat.’’ One of the oldest measures of temperature is 
that of its effect on the bodily sensations; and in the past, gen¬ 
erations of bakers have been in the habit of judging and de¬ 
termining the temperature of their doughing water by im¬ 
mersing the aiTn in it. For many reasons this is at best but 
an inaccurate method. First of all, because two individuals 
are not necessarily in the same degree sensitive to warmth. 
Imagine a case in point. The foreman of a bakery today tells 
workman A to make a dough and instructs him to use water 
just comfortable when tested with the arm. TomoiTOw he 
sets workman B to the same task and with the same instruc¬ 
tions. But it is veiy doubtful whether A and B have the 
same conceptions of a degree of warmth which is “comfort¬ 
able.” Further, the same man will feel a different sensation 
of warmth according to his state of health; if he has a cold 
everything feels chilly; if he is feverish everything is unduly 
hot. Even natural surroundings may similarly warp his judg¬ 
ment. Set a man for some hours to take stock of goods in an 


76 



BREAD-SHOP PRACTICE 


ice-cold storage chamber and then transfer him to a moder¬ 
ately waiTn room—he will regard it as pleasantly warm. Next 
let him engage in some task in a very hot room, possibly an 
engine room or boiler house. If after a time he comes back 
to the same moderately warm room, the warmth of which has 
not changed, he will regard it as delightfully cool. 

Some better method of measuring temperature is eminently 
desirable, and one of the most useful is that, as already men¬ 
tioned, bodies increase in volume as they become wanner, 
solids as a rule least, then liquids, and next gases. There are 
two liquids which are used for this purpose almost to the ex¬ 
clusion of all others. 

The first of these is the metal mercury; this does not boil 
until it gets at a fairly high temperature, but it freezes com¬ 
paratively readily, though still at a much colder point than 
does water. The other liquid is alcohol, which boils some¬ 
what readily but is only frozen by extreme cold. If you could 
take a cupful of cold mercury and warm it to the tempera¬ 
ture of boiling water, the increase in volume would not be 
perceptible by simply looking at the liquid in the cup. So the 
scientist adopts a very simple but ingenious method of ren¬ 
dering this expansion easily visible. A glass tube is taken 
with a very small bore; on the end of this a relatively large- 
size bulb is blown. This is filled with mercury, say, to one- 
third of the length of the stem. Means are next taken to drive 
all the air out of the upper part of the stem, the top of which 
is then sealed by fusing the glass. If this piece of apparatus 
be taken and held in the warm hand all the mercury expands, 
but as it is rigidly bound in every direction but up the narrow 
tube, it ascends the stem and so demonstrates that it experi¬ 
ences an increase in temperature. The student will probably 
have recognized the instrument which has just been described 
and knows it as a 'Thermometer.'' 

We have now got so far as the thermometer in its simplest 
form, that is, a bulb blown on the end of a narrow bore glass 
tube, the whole being partly filled with mercury. The student 
is not very likely to be in possession of such an instrument, 
and if not, let him take an ordinaiy thermometer and ignore 
for the moment the graduated scale of the instrument. Plunge 


77 



BREAD-SHOP PRACTICE 


the thermometer in a vessel of cold water and wait till the 
level of the mercury in the stem is stationary. When this is 
so, the thermometer and the water are at the same temper¬ 
ature. With a glass-marking pencil or ink make a mark show¬ 
ing the height of the mercury. Bear in mind that through 
any mass of matter which allows free transference of heat 
there is a tendency to equalization of temperature. Conse¬ 
quently the thermometer and the water in which it is im¬ 
mersed assume the same temperature, whichever is the hotter 
yielding heat until the equilibrium is reached. Having marked 
the height of the mercury, transfer the instrument to a sec¬ 
ond vessel of w^ater; the mercury either remains stationary^ 
or rises or falls. In the former case the two vessels of water 
are at the same temperature; with a rise the second vessel 
is the warmer, or with a fall the second is the colder. In this 
way the broad fact of higher or lower temperature is easily 
ascertained. 


System of Graduating Thermometers. 

To go any further, some system of graduation is necessary. 
For this purpose we require some fixed points of temperature 
that can be readily obtained; and accordingly the melting 
point of ice (commonly called the freezing point of water) 
and the temperature of steam from boiling water (commonly 
called the boiling point) are in general use. The student may 
verify these for himself. Let him take some ice and pound 
it into small fragments and mix with cold water. On being 
stirred this soon acquires a uniform temperature, and a ther¬ 
mometer plunged in the mixture soon becomes stationary. If 
the position of the mercury on the scale is noted, it will be 
found to coincide with a mark frequently denominated the 
‘"freezing point.” For the next purpose, a (lask should be taken 
sufficiently large to take in the whole of the theiTndmeter, 
with the bulb just above the surface of some water wliich it 
contains. The water is gradually brought to the boil and the 
mercury rapidly rises in the current of steam. Again a star 
tionary point is reached, and this coincides with a mark fre¬ 
quently denominated the “boiling point.” Note where the 
mercury actually is. For absolute accuracy it is important 


78 



BREAD-SHOP PRACTICE 


to make this experiment with the barometer at the height of 
760 millimeters or 29.92 inches. The reason for this is that 
the higher the barometer the higher is the temperature of 
ffteam in contact with boiling water. (For reasons which 
cannot be further dealt with here,, the freezing and boiling 
points are deteiTnined in the manner described). 

Some scale is necessary in order to register other temperar 
tures, and Fahrenheit divided the distance between the freez¬ 
ing and boiling points into 180 equal parts or “degrees.^^ He 
then set off degrees of equal value both below the freezing 
and above the boiling points. When the mercury had fallen 
below the freezing point to so far as 32 of these degrees, he 
regarded the zero of temperature as having been reached and 
accordingly marked this point as nought or 0. Then he counted 
upwards, and the freezing point became 32 degrees (32°) and 
the boiling point 32 + 180 == 212 degrees. Degrees above the 
boiling point become 213, 214, etc., as far as it is desired to 
register temperature. Now the zero of the Fahrenheit ther¬ 
mometer is by no means the most extreme cold experienced, 
and so, to register this, degrees of the same value are marked 
below the zero, and counted as minus degrees, or so many 
below zero. Thus, 10 such degrees become—10°, and so 
on. 

The Fahrenheit scale seems somewhat arbitrary, as there is 
no very apparent reason for the division of the range from 
freezing to boiling points into 180 degrees. For scientific pur¬ 
poses another scale is now widely used, i.e., that of Celsius, 
known as the Centigrade scale. In this case the freezing point 
is taken as 0 or zero, and the boiling point as 100, the range 
being divided into 100 degrees. Degrees below the freezing 
point of water are reckoned as minus degrees, and those above 
the boiling point simply count upwards. The student may 
refer again to his thermometer, and especially to the noted 
points for freezing and boiling, respectively. If the thermo¬ 
meter be a Fahrenheit he will find them to be 32 and 212; if 
a Centigrade, 0 to 100. The scales are indicated by the use 
of the letters F. or C. after the number of degrees in each 
case. 


79 






BREAD-SHOP PRACTICE 


Converting One Scale Into the Other. 

It frequently becomes necessary to convert one scale into 
the other. Thus a text-book may direct a certain operation 
to be conducted at 25°C., while the worker has only a ther¬ 
mometer graduated in Fahrenheit degrees. The one has then 
to be translated into the other. First of all, as 100 Centigrade 
degrees are equal to 180 Fahrenheit degrees it follows that 1 
degree Centigrade equals 1.8, or 9/5 Fahrenheit degrees. Con¬ 
versely, 1.8 Fahrenheit degrees equal 1.0 Centigrade degree (1 
Fahrenheit degree equals 0.55 centigi’ade degree, but this is 

rarely used in calculations, being a recurring decimal. The 
corresponding vulgar fraction is 5/9). Evidently 25 Centi¬ 
grade degrees must amount to 25X1.8=45 Fahrenheit 
degrees, and 25*’C. must be equivalent to 45 Fahrenheit 
degrees above the freezing point. But as the Fahrenheit freez¬ 
ing point is 32 on the scale, it is plain that 32 must be added 
to the 45, and we have 45 + 32 = 77. That is, 25°C. equals 
77°F. To change from Fahrenheit to Centigrade is just the 
opposite operation. Taking 77°F., let us see how the Centi¬ 
grade equivalent is reached. First of all, 32 must be deducted 
so as to find how many Fahrenheit degrees there are above the 
freezing point. 77—32=45. Then, as 1.8 Fahrenheit degrees 
equals 1 Centigrade, 45 must be divided by 1.8 thus: 45-1-1.8 
=25, which number is the corresponding one on the Centigrade 
scale. These methods of calculation are embodied in the fol¬ 
lowing formulas, in which both the decimal and vulgar frac¬ 
tions are given. 

Centigrade to Fahrenheit. 

C.° X 9 

: (C.° X 1.8) + 32 = F: or-4- 32 = F.° 

5 

Fahrenheit to Centigrade. 

F.° —32 (F.° —32)X5 

-= C.° or-- C.° 

1.8 9 

It is very necessary for the student to grasp thoroughly 
this question of converting these scales, since he may fre- 


80 







_ BREAD-SHOP PRACTICE _ 

quently find it most important to make the calculation at a 
moment’s notice. 

Quantity of Heat—Modes of Measurement. 

We have now got so far as to know how to measure and 
record heat intensity or temperature; but this does not take 
us all the way, since the thermometer is not affected by quan¬ 
tity of heat. Let us make this clear. If a thermometer be 
plimged into either one pint or ten pints of boiling water, the 
instrument will in each case stand at the boiling point. Yet 
it is evident that the larger quantity must contain ten times 
as much heat as the smaller. And if two such vessels of cold 
water are heated by a constant source of heat, as for example 
a gas burner, the larger will take ten times as long to reach 
the boiling point (any error of experiment being allowed for). 
The student may be interested in verifying this for himself, - 
in which case his simplest course is to take a saucepan with a 
capacity of about three pints. Let him pour in a pint of cold 
water, noting the temperature and time. Then bring the 
water to the boil by means of a Bunsen burner and notice how 
long it takes. Cool down the saucepan, pour in two pints of 
cold water at the same temperature as before and heat in 
the same way. It will take just twice as long to get to the 
boil, barring any slight variations due to error of experiment 
and possible disturbing causes which need not be gone into 
. further at present. 

Now, quantity of heat is just as important a measure to 
the baker as temperature, and so must be just as carefully 
studied. Quantity of heat is measured by the amount neces¬ 
sary to raise a certain weight of some body from one to 
another fixed temperature. Water is the substance usually 
selected, and the amount of heat necessary to raise 1 gram of 
water from 0° to 1° C. is termed a unit of heat or a calorie. 
From this it follows that to raise 2 grams of water from 0“ 
to 1° C. will require 2 units of heat or 2 calories. Between 
0° and 100° C., approximately the same amount of heat is 
necessary to raise 1 gram of water through any 1 degree of 
temperature, so that to raise 1 gram of w^ater through 2 de¬ 
grees will also require approximately 2 calories. For practical 


81 




BREAD-SHOP PRACTICE 


purposes it follows that the weight of water in grams, multi¬ 
plied by the number of degrees of temperature through which 
it must be raised, gives the number of calories required. 

Specific Heat. 

We next come to another important function of bodies, 
which is known as their specific heat. The same weights of 
different bodies require different quantities of heat to raise 
them through the same range of temperature. The quantity 
of heat necessary to raise 1 gram of any substance through 1 
degree of temperature is termed its specific heat. The specific 
heat of water is taken as 1 or unity. The following are the 
specific heats of a few important substances: 

Water. Alcohol. Glass. Iron. Mercury. 

1.00000 0.61500 0.19768 0.11379' 0.03332 

This means that 1 gram of glass, for instance, requires 
only 0.19768 of the quantity of heat that is necessary to raise 
1 gram of water through a degree in order to raise its tem¬ 
perature the same amount. Conversely, the heat that will 
raise 1 gram of water through a degree will raise 1 gram of 
glass through about five degrees. 

Our next step must be to investigate the resultant temper¬ 
ature of various mixtures. If ten parts of water at any de¬ 
sired temperature be mixed with ten parts at some other tem¬ 
perature, the temperature of the resultant mixture is a mean 
between the two. Thus, if 10 grams at 20° C. be mixed with 
10 grams at 80° C., the result is 20 grams of water at a tem¬ 
perature of 50° C. If the quantities are unequal, another ele¬ 
ment enters into the calculation, but the principle of its solu¬ 
tion is just the same. Let us take an example: 10 grams of 
water at 15° C. are mixed with 4 grams at 40° C. What is the 
temperature of the resulting mixture? The simplest plan is 
to look at the number of units of heat each contains, reckoned 
from 0° C., and this is set out below: 

10 grams at 15° C = 10 x 16 = 150 heat units 
4 grams at 40° C. = 4 x 40 = 160 heat units 


14 grams containing 


82 


310 heat units 







BREAD-SHOP PRACTICE 


The 14 grams therefore contain altogether 310 heat units, 
and 1 gram will contain 310 divided by 14, which equals 22.1 
heat units. As each heat unit to a gram represents 1 degree 
in temperature above 0% the temperature of the mixture must 
be 22.1“ C. Now, supposing the quantities were pounds, or 
gallons, or any other measure the same rule holds good; 10 
gallons at 15° mixed with 4 gallons at 40° will yield 14 gallons 
at 22.1° C. Take in fact any unit quantity of water, a gallon 
if wished; that unit requires a definite quantity of heat to 
raise its temperature 1 degree. Then, so long as you are deal¬ 
ing with any number of the same unit, the quantity of heat 
necessary to raise the unit quantity of water may be taken 
as the relative heat unit for that amount of water. The 
student of algebra will understand this if put another way. 

1 gallon of water at 1° C. contains x heat units (or 1 H. U. of 
X calories). 

10 gallons of water at 1° C. contain 10 x heat units. 

10 gallons of water at 15° C contain 10 x 15 x heat units. 

4 gallons of water at 40° C. contain 4 x 40 x heat units. 

On mixing these, the mixture will consist of 14 gallons 
containing: 

10 X 15 = 150 X H. U. -f 4 X 40 = 160 X H. U. = 310 x H. U. 
And per gallon there must be: 

310 X H. U. 

-= 22.1 X H. U. 

14 

The unknown quantity x is a constant throughout the whole 
of the calculations, and so in comparing the relative figures 
obtained at each stage may be eliminated. This brings us 
back to the simple original heat unit calculation. 

When, however, we have to deal with mixtures of differ¬ 
ent substances and at different temperatures, the problem 
becomes more complicated. As an example, 600 grams of 
water at 60° C. are poured into a glass beaker weighing 92 
grams and at a temperature of 15° C. The water will be some¬ 
what cooled and the glass of the beaker warmed until they 
both attain the same temperature. What will be the temper¬ 
ature? The vessel and water may be looked upon as a com- 


83 





__ BREAD-S H OP P R ACTICE __ 

bination or mixture of water at 60° and glass at 15 , their total 
heat being distributed so as to produce equal temperature. 
Starting from 0° C., the water must contain the following heat 

units: 

600 X 60 = 36,000 H. U. 

The glass must contain an amount of heat best detennined 
by just calculating its equivalent in water. As glass has a 
specific heat of 0.19768, that figure multiplied by 92 gives the 
weight of water that contains the same amount of heat per 
degree as 92 grams of glass. Then 

92 X 0.19768 = 18.18656 

That is to say, to raise that glass beaker through 1 degree 
requires the same amount of heat as would raise 18.18656 
grams of water through 1 degree. As, however, the beaker 
to start with is at 15°, the above figure must be multiplied by 
that number: 

18.18656X15=272.79840 H, U. 

Thus, in the mixture of water and glass we have 

600 X 1.0 X 60 = 36,000.000 H. U. 

92 X 0.19768 X 15 = 272.798 H. U. 

The mixture, 36,272.798 H. U. 

This is distributed between 600 grams of water and 92 
grams of glass, which equal 18.186 grams of water, or a total 
of the two, reckoned in terms of water, of 618.186 grams. 
Then, dividing the total of heat units by the total of sub¬ 
stances in terms of water we have 

36,272.798 

-= 58.6 per water-gram. 

618.186 

As we have already seen, this figure is that of the temper¬ 
ature, and accordingly the water is cooled down from 60° to 
58.6° C. by the cold beaker into which it is poured. The extent 
of cooling is less than most people would suppose. This ex¬ 
ample has been taken with a very definite object, because the 
baker has to consider and allow for the cooling effect of his 
troughs, etc., on his water or other warm materials. We will 
take another instance. The iron trough and blades of a dough 
mixing machine weigh altogether 500 pounds and are at a 


84 








- BREAD-SHOP PRACTICE _ 

temperature of 16° C. Into this is poured 150 pounds of water 
at a temperature of 30° C. It is required to find the amount 
of cooling produced by the mixing machine. First bear in 
mind, as explained, that with the same units of weight 
throughout the quantities may be regarded for heat unit pur¬ 
poses as grams. We then have exactly the same kind of cal¬ 
culation as for the glass beaker: 

150 X 1 X 30 = 4,500 H. U. in water. 

500 X 0.11379 = 56.895 pounds water equivalent of iron of ma¬ 
chine trough, etc. 

600 X 0.11379 X 16 = 910.32 H. U. in iron of trough. 

That is to say, in the mixture of water and iron we have 
4,500 H. U. in water 

910.32 H. U. in iron of trough. 


5,410.32 H. U. in mixture. 

The total of water and iron of trough reckoned as water is 
150 -f 56.895 = 206,895^pounds. Then, dividing the total of 
heat units by the total of substances in terms of water we 

have: 

5,410.32 

-= 26.1 

206.895 

As already explained, this figure, 26.1, is the temperature 
of the mixture. In other words, the water has been reduced in 
temperature from 30° to 26.1° C. by the heat it has imparted 
to the iron of the machine or the water has lost approximately 
4 degrees in temperature through contact with the machine. If 
required to be at a temperature of 30° when in the machine, 
it would have to be taken at approximately^ 34° before being 
added. Probably the weight taken as that of the iron of the 
machine is rather higher than the average. It will be a good 
exercise for students to make a precisely similar calculation 
except that the iron trough, etc. of the machine is assumed to 
weigh 300 pounds. 

These calculations may very profitably be supplemented by 
an actual series of tests made with a doughing machine. If 
the machine has been standing unused for, say, over an hour. 


85 









BREAD-SHOP PRACTICE 


it may be taken that its temperature is the same as that of the 
bakery. If there is a water-measuring tank the temperature 
of the water and the quantity can be easily read off. Add a 
measured quantity of warm water to the machine and note 
how much it is reduced in temperature. If there is no such 
tank, mix the measured quantity of water in a tub, take its 
temperature, and pour into the machine. Observe as before 
how much the water is lowered in temperature. 

The whole of this matter has been described at length be¬ 
cause it is essential that the competent baker knows all he can 
about the various factors that affect his temperatures. Ef¬ 
ficient control of these governs largely the question of the 
quality of his bread. 

We must next deal with the most important of all mixtures 
to the baker, i. e., that of flour and water, which forms his 
dough. 

Taking in the first place mixtures of flour and water of 
the same temperature, it is plain that that of the mixture 
will be the same unless heat has been gained from, or lost to, 
surrounding bodies during the act of mixing. (Possible 
sources of change are, first, chemical reactions which may 
take place between the substances mixed, and second an ac¬ 
tual wanning by the friction of the materials in the process 
of mixing. Such changes are not, however, very great, and 
need not be discussed at this stage.) 

Mixing Ingredients of Different Temperatures. 

The next step is to observe the temperature of a mixture 
when flour and water have been taken at different tempera¬ 
tures. Experiments have been made with this object in view, 
and the student may very profitably repeat some of these. 
First, weigh off 500 grams of flour. Then weigh an earthen¬ 
ware basin, large enough to mix 1,000 grams of dough. Weigh 
off into this basin 500 grams of water at 150 degrees Fahr. 
(or the corresponding number of degrees C.). Stir the water 
round in the basin by a spatula (stirrer) of bone or wx)od. 
Take the temperature of the flour, which may be, say, 67 • 
degrees Fahr. This should be done with a delicate thermome¬ 
ter, having its bulb exposed. Stir the flour with the instru- 


86 




BREAD-SHOP PRACTICE 


merit until the mercury becomes stationary and then read off 
and make a note of the temperature. Next make a second 
reading of the water in the basin, which will probably have 
cooled slightly by imparting some heat to the basin itself, say 
to 145 degrees Fahr. At once add the flour and thoroughly 
mix into a dough. Take temperature of this by plunging 
the thermometer into it. Let the mercury become stationary; 
withdraw it and plunge into another place, it will probably 
slightly rise or fall. Do this two or three times, until the 
mercury does not move on being replunged. Read off the 
temperature, which will be that of the dough. (A chemical 
thermometer graduated on the stem is the best for this pur¬ 
pose. These thermometers are blown so that the outside di¬ 
ameter of the bulb, which is elongated, is the same as that of 
the stem). If flour and water have the same specific heat the 
temperature of the mixture should be a mean between that 
of the flour and water, 

145 4-67 

that is -— 106. But on making such an experiment, 

2 

the dough will be found to be considerably warmer; in one 
such detemiination, the writer got the result of 118 degrees 
Fahr. A moment's thought will show that the water must 
therefore have a higher specific heat than the flour. On mak¬ 
ing a similar experiment wdth flour at the same temperature, 
and water at 104 degrees Fahr., the resultant dough was at 
93 degrees Fahr., which figure approaches more closely that 
of bakery practice. 

Calculating Specific Heat of Flour, 

Let us see how the specific heat may be calculated from 
these figures. First of all, 500 grams of water have fallen from 
104 degrees to 93 degrees, or through 11 degrees; that is to 
say, the water has parted with 500 x 11 = 5,500 H. U. That 
. number of H. U. has been imparted to 500 grams of flour, and 
has raised it from 67 degrees to 93 degrees, or through 26 
degrees. This is equivalent to raising 500 x 26 = 13,000 
grams through one degree, and to do this 5,500 H. U. have been 


87 






BREAD-SHOP PRACTICE 


required. To raise 1 gram through 1 degi’ee, there will have 

5,500 

been required -= 0.42 H. U. According to our defini- 

13,000 

tion, this figure 0.42 is the specific heat of flour. The author 
has made a large number of experiments of this description, 
both on the small scale and also on machine-made doughs in 
the bakery. No attempt was made to eliminate various disturb¬ 
ing influences, as the object was rather to get what may be 
called a baker’s working specific heat for flour. The resultant 
figures ranged from 0.30 to 0.45, but most of them approxi¬ 
mated very closely to 0.40 and that figure may usually be 
taken as the working specific heat of flour. From this it fol¬ 
lows that 1 unit by weight of water in falling (or rising) 
through 1 degree raises (or cools) 2.5 units by w’eight of flour 
through 1 degree of temperature. 

Applying This Knowledge in Practice. 

Let us see how this can be applied in practice. Flour hav¬ 
ing stood for some time in the bakery soon becomes fairly 
warm, and may very easily have a temperature of, say 70 de¬ 
grees Fahr. If a dough is required to have a temperature of 
85 degrees Fahr., the baker knows by experience what should 
be the temperature of the water to produce the desired result. 
But suppose in winter a carload of flour arrives which has been 
on the rails for some days and has to be used at once. Assum¬ 
ing that such flour is at 32 degrees F’ahr., at what tempera¬ 
ture must 100 pounds of water be taken to make a dough with 
196 pounds of flour that shall have a temperature of 85 de- 
gi’ees? To begin, 196 pounds of flour have to be raised from 
32 degrees to 85 degrees, that is, through 53 degi’ees. Flour 
having a specific heat of 0.40, 196X0.40=78.4, which is the 
equivalent weight in water to be raised through 53 degrees, 
and 78.4X53=4155.2 H. U., which will be required in order to 
accomplish this. But 1 pound of water liberates a H. U. in 
falling through a degree, and consequently 100 pounds of 

4155.2 

water falling through -= 41.552 degrees will yield the 

100 


88 






BREAD-SHOP PRACTICE 


necessary number of H. U., so that the water must be taken 
at a temperature 41.5 degrees above 85 degrees, that is at 126.5 
degrees. For the moment, nothing is being said as to the 
limits of temperature, which require to be observed for other 
reasons. 


An Ingenious Baker’s Thermometer. 

An ingenious method of graduating thermometers has been 
recently introduced for the use of bakers. The general prin¬ 
ciple is based on providing for a dough of definite temperature, 
say, 80 degrees F'ahr. Then in use the temperature of the 
flour is taken by the instrument and read off on an ordinary 
thermometric scale on the right-hand side of the stem. On its 
left-hand side is arranged a scale of water temperatures that 
should make a dough of the desired temperature. Thus, sup- 
post the flour registers 52 degrees, then according to the scale 
on the instrument the water should be taken at 95 degrees. 
In the tests made by the writer, and before referred to, in one 
experiment on a large machine-made dough, the temperatures 
were, respectively flour 52.5 degrees, water 95 degrees, and 
dough 79 degrees, Pahr. These.figures practically coincide 
with those afforded by the special scale on the thermometer 
referred to. 

Calculating Water Temperature for Dough Temperature. 

If such an instrument be taken as a practical bakery guide, 
or even without it, in the case of ordinary work the problem 
arises: I want one dough, say, to be at 80 degrees but it is 
necessary that the next one be at 85 degrees, what is the cor¬ 
rect water adjustmenc of temperature to secure this figure? 
The simplest method of obtaining an answer is to go back 
to first principles. You have your dough at 80 degrees, what 
will be the effect of raising the temperature of the water one 
degree? For purposes of such calculations as the present it 
may be taken that 1 part of water to 2 parts of flour are used 
in making dough. Then, the water being one degree hotter 
introduces an extra H. U. to be divided up between itself and 
2 of flour. Hence: 


89 



BREAD-SHOP PRACTICE 


. 2 of flour, sp. ht. 0.4 equals in water.0.8 part 

1 of water, sp. ht. 1.0 equals in water.1.0 part 


1.8 parts 

As 1 H. U. has to be divided over 1.8 parts, then the in- 

1.0 

crease of temperature of the mixture must be—=0.55 recur- 

1.8 

ring, which is the increase of temperature of the whole dough 
caused by one degree increase in that of the water. For this, 
a working rule is to take it that the increase in temperature 
of the dough is half the increase in that of the water. From 
this rule, in order that the next dough be at 85 degrees, that 
is, five degrees increase, the water must be taken at 10 de¬ 
grees hotter. If the more exact figure of 0.55 be taken, then 
the more precise figure of 9 degrees hotter water will suffice 
to raise the temperature of the dough by 5 degrees. 

A point sometimes raised here is, how far does this rule 
hold with a very slack dough ? With English stiff doughs, water 
is commonly taken at the rate of 56 quarts (140 pounds) to the 
sack, 280 pounds of flour, which is exactly 1 to 2, the equiva^- 
lent American quantities being 98 pounds of water to 196 
pounds of flour. From American recipes before me I get a 
variation of water as follows: 

105 pounds water per barrel flour=l part of water to 1.87 
flour. 

117.6 pounds water per barrel flour=l part of water to 1.66 
flour. 

Taking the larger proportion of the two, 117.6 pounds, and 
making the same calculation as before, we have: 


1.66 of flour, sp. ht. 0.4 equals in water.0.66 part 

1 of water, sp. ht. 1.0 equals in water.1.00 part 


1.66 parts 

As 1 H. U. has to be divided among 1.66 parts, the increase 

1.0 

of temperature of the mixture must be-=0.602, which is 

1.66 


90 









BREAD-SHOP PRACTICE 


the increase of temperature of the whole dough, caused by one 
degree increase in that of the water when used at the rate 
of 117.6 pounds per barrel. This figure is slightly higher 
than the previous one. The actual working difference is f^ly 
expressed by the statement that at 98 pounds per barrel, 10 
degrees increase in temperature of the water raises that of the 
dough by degrees, and that at 117.6 pounds per barrel 10 
degrees increase in temperature of the water raises that of the 
dough by 6 degrees. Intermediate quantities would be pro¬ 
portionately between. 

Summaiy. 

WaiTnth of doughing water. 

Scientific principles underlying warmth. 

Warmth and heat; effects of heat. It has no weight. 

Temperature is the measure of warmth. Bodily sensa¬ 
tions are not a good guide. Better method is the expansion 
of liquids. This implies the thermometer. 

An ungraduated thermometer can show generally whether 
two masses are at the same or different temperatures. 

For accurate readings of temperature some system of 
graduation is necessary. The start is the two fixed points 
commonly known as the freezing and boiling points. The dis¬ 
tance between is divided into varying numbers of equal parts 
called degrees. Two such systems are known respectively as 
those of Fahrenheit and Centigrade scales. Conversion of 
one of these into the other. 

Quantity of heat, modes of measurement of: Unit of heat 
or calorie. 

Specific heat. Its relation to the resultant temperature 
of mixtures. Bearing of this on cooling effect of glass, iron, 
and other vessels used for holding waim water. Calculations 
based thereon. Experimental deteiTnination of cooling effect 
of metal of dough mixing machine. 

Flour and water of the same temperature on being mixed 
show no change except such as may be due to chemical reac¬ 
tions between the ingredients and possibly heat generated by 
friction of mixing. 

Temperature of dough resulting from mixtures of flour and 
water at different temperatures. Experimental determinations 


91 



BREAD-SHOP PRACTICE 


of same. Determination of specific heat of flour by method of 
mixings. 

Practical application of specific heat calculations. 

Thermometer for regulating temperature of water by that 
of flour. 

Calculations of variations of water temperature to produce 
a definite alteration in dough temperature. 

Working rule as to same, and how affected by the use of 
very slack doughs. 




92 



CHAPTER VII 

TEMPERATURE AND FERMENTATION 

Effect of Temperature on Fermentation of Dough. 

Having studied the question of the control of temperature 
in the matter of dough making, we come to the larger problem 
of fermentation itself and how governed by temperature. 
Dough essentially consists of a mixture of flour, water, yeast 
and salt, with some forms of sugar and fat, usually but not 
invariably, added. In the simplest form of bread-making the 
baker makes this mixture so as to have the desired tempera¬ 
ture, say, from 80 degrees to 85 degrees Fahr., and puts it in 
a trough which stands in a reasonably warm place. 

The student already knows that yeast causes fermentation 
in a warm solution containing sugar, and also that thereby 
the sugar is decomposed into alcohol and carbon dioxide gas. 
The baker knows that his dough which he has made slowly 
grows in volume, and when cut is seen to be distended with 
small bubbles of gas. Further, if it is “punched” with the 
hands and arms the gas escapes with an audible sound and 
the dough shrinks in size. Evidently, however, the action of 
the yeast is not exhausted, for in a while the dough again 
swells in volume or becomes “proofed” as the baker calls it; 
and this process of knocking out the gas and allowing a further 
volume to be generated may be repeated several times, in fact, 
until all available sugar is consumed. 

When Dough Is at its Best Condition. 

One of the most important parts of the baker’s craft is to 
know just exactly what is the best stage at which to take this 
fermenting dough and make it into loaves ready for the oven. 
The student may gain much useful information on this point 
by an actual baking experiment such as the following: 

Make about 20 pounds of flour into a slack dough, which is 
fairly warm (say 90 degrees Fahr.), and with a full amount of 
yeast, say 3 ounces. Cut off a piece directly the dough is made, 
and bake immediately. The result will be a close small, very 
moist loaf, not much bigger than the piece of dough cut off. 


93 


BREAD-SHOP PRACTICE 


Then make and bake an additional loaf at the end of every 
hour, meanwhile keeping the main mass of dough in a warm 
place. . For some hours the loaves improve in boldness, then 
remain stationary and finally become runny and flat. The 
crust is at first brown or ^Toxy,^' then of a golden yellow, and 
finally abnormally pale. The interior of the loaf improves in 
character during the first three or four of the series, acquir¬ 
ing more bloom, then changes to a grayish white, and after¬ 
wards ^'saddens'" and darkens into a dull cold gray, merging 
ultimately into a brown. At the same time it becomes ragged 
on the outside edges, and dark where two loaves have touched 
each other in the oven. In flavor the first loaf will be sweet, 
but raw and “wheaty,” characteristics which will be lost 
as fermentation proceeds. At its best the raw taste will have 
gone, leaving only a sweet, clean-palate flavor. This will be 
succeeded by a gradual disappearance of the sweetness, the 
bread being neutral and tasteless; at the same time the loaf 
will have lost its moistness and will be harsh and crumbly. As 
fermentation is pushed still further, the bread commences to 
taste of the yeast but this is governed somewhat by the origi¬ 
nal soundness or otherwise of the yeast. This condition 
merges into one of slight sourness, gradually becoming worse 
until, finally, not only is the taste offensive, but so also is the 
smell, partaking not only of sourness in character, but also of 
incipient putrefaction and decomposition. During these latter 
stages the bread again becomes soft and clammy. 

Such are in brief the changes observable in dough under 
ordinary conditions of working, from the first start of fermen¬ 
tation to the actual commencement of putrefaction. These 
may be slightly modified by the character of the flour and 
other constituents of the dough; but if the conditions of fer¬ 
mentation be healthy and noiTnal, the whole series of changes 
substantially follows the order given above. 

One thing is at once taught by such an experiment, and 
that is that there is a best time to take the dough and make 
it into loaves. Taken too soon, the bread is deficient in bloom 
of crumb, the crust is of an unpleasant red, and the flavor is 
raw in character. At the right time the crust should be of a 
rich yellow tint, the crumb evenly vesiculated and with a 


94 




BREAD-SHOP PRACTICE 


creamy bloom, while the flavor is sweet and clean on the palate. 
Allowed to lie too long, the crust becomes pale and has a 
washed-out appearance; the crumb may be whiter, but the 
bloom is gone, and is likely to be disfigured by large holes; it 
is altogether coarse in appearance. Further it becomes 
harsh, dry, and crumbly. In flavor the bread is at first taste¬ 
less but this is followed by a stage in which it is actually sour. 
Obviously, the baker aims at taidng the dough when just at 
the right age. 

Objects of Dough Fermentation, 

Before saying anything else, it is well to mention that 
bread fermentation is not simply a process for the production 
of gas for the purpose of aeration. Other changes are also 
going on, some of the sugar, dextrin and soluble starch is 
being used up, and so clamminess is being removed. Fermen¬ 
tation also affects the gluten, a change which the baker refers 
to as the ripening of the dough. Hard glutens soften, and the 
dough, instead of being short and tough, becomes soft and 
elastic. At the same time there is a loss of the rawness, and 
this also is an effect of the yeast. A time is elected at which 
all these actions have produced their best results. 

How Is Time of Readiness Determined? 

. How is that time determined? The modern baker is for¬ 
tunate in that his flour and yeast in particular are much more 
regular than was at one time the case. Hence if he keeps his 
temperature right, the time taken for a dough to arrive at per¬ 
fect maturity remains fairly constant. He knows by expe¬ 
rience what the best time is, and is usually justified in taking 
the dough when that time elapses. There are, however, cer¬ 
tain physical characteristics which are a guide in forming a 
judgment. The volume of the dough is one of these, and many 
ba'kers are guided by the rise and fall of the dough in the 
trough as fermentation goes on and the gas from time to time 
escapes. This rule applies more, however, to a ‘"sponge,” in 
which mode of bread-making a very slack dough is first made 
with all the yeast and some of the flour and afterwards more 
flour and water worked in. Sponge and dough methods are not 
now so common as formerly but when used the baker often 


95 




BREAD-SHOP PRACTICE 


decides by when the sponge has dropped once or risen twice 
whether or not it is ready. These tests depend more or less 
on local conditions; thus, a sponge will fall more quickly in a 
broad, shallow trough than in a-narrow, deep one, since the 
larger the surface the sooner will the gas break through and 
escape. In a straight dough the baker may be guided by the 
feel of the dough; it should be elastic and resilient when 
punched. If a piece be pulled asunder, the dough should have 
just the right amount of elasticity and its texture should be 
smooth and silky. On being cut the gas cells should be small 
and even. Further, the odor emitted from the cut should be 
ripe and sweet. 

Another test is sometimes employed which is not so well 
known, but is of assistance to bakers when perhaps a little 
puzzled. As the result of fermentation dough rises in tempera¬ 
ture ; the amount of such rise varies under different conditions, 
but under the same conditions is fairly constant. Tlius if a 
dough is at 85 degrees Fahr. when made, it may be at 88 de¬ 
grees Fahr. when ready. This figure being known, it usually 
follows that when the lise in temperature is three degrees the 
dough is at the same stage of readiness. This test is of value 
when unsatisfactory bread is being produced. When the 
temperature nse is normal, it is rare that faulty bread is due 
to any defects in the yeast. All this may seem very difficult to 
the student, and yet it is one of the things he must master. 
The capacity for accurate judgment can only be acquired by 
close observation and experience, and it is the possession of 
this faculty which makes the good baker the craftsman he is. 

Conditions Affecting Speed of Fermentation. 

It is well here to sum up the conditions which affect the 
speed of feiTnentation. The student knows already that tem¬ 
perature is one of the most important of these. There follows 
a summary of those conditions which accelerate and those 
which retard fermentation. 

Acceleration of Fermentation. 

Yeast.—The greater the quantity, the more quickly does 
fermentation proceed. Greater strength of the yeast itself 
also accelerates. 


96 




BREAD-SHOP PRACTICE 


Flour.—Soft flours ferment the more rapidly. They contain 
more sugar and easily convertible starch. Their nitrogenous 
matter is more likely to act as a yeast stimulant. The soft¬ 
ness of their gluten is a less physical obstacle to the action of 
yeast. 

Potatoes, Sugar and Saccharine Extracts.—All these tend 
to stimulate yeast and so augment the speed of fermentation. 

Water.—This acts in virtue of the quantity used. The slack 
doughs ferment more rapidly. 

Aeration.—The presence of free atmospheric oxygen acts 
as a stimulant to yeast. Hence the advantage of thor¬ 
oughly sifting the flour immediately before use. Also the 
“cutting over” and exposing the interior of the fermenting 
dough to air acts in the same way. 

Temperature.—This governs all. With low temperatures 
there is little if any fermentation, and with higher tempera¬ 
tures it proceeds more rapidly. For this reason temperature 
has been studied so closely. 

Retardation of Fermentation. 

These may be summed up as the opposite of accelerating 
conditions: 

Yeast, weak or in small quantity. 

Hard, dry flours. 

Lessening of potatoes, sugar, and other stimulants. 

Stiff, unaerated doughs. 

Low temperature. 

Salt.—This is essentially a retarding agent. 

There is an old European saying that “All roads lead to 
Rome,” and, so far as it is safe to generalize, one may also say 
“All bakery problems lead to temperature.” So sweeping an 
assertion may go beyond the literal truth, but it conveys an 
idea of how important thei problem of temperature is in suc¬ 
cessful baking. We have now traced out the various matters 
which have to be considered and allowed for in order to get a 
dough at the desired initial temperature when made. We have 
in particular studied the nature of mixtures of flour and water 
in the matter of temperature and the cooling effects of con¬ 
taining vessels. 


97 




BREAD-SHOP PRACTICE 


Modifying Controlling Factors. 

Going now a step further, there is a certain temperature 
which may be regarded as the ideal one for a dough. Let us 
suppose for a moment that that is 25 degrees C. Why is it 
that the baker sets his doughs at temperatures which vary 
from this figure? Bake shop exigencies require that doughs 
shall follow one another at fairly regular intervals. If the first 
one is wanted in six hours, the next may be required in seven 
hours, or say at successive intervals of an hour. If all these 
doughs are machine-made one after the other as quickly as 
possible, it is very easy to make at least one per twenty min¬ 
utes. Obviously, while the first will have to lie six hours, the 
next will have to lie six hours and forty minutes, and a third 
one seven hours and twenty minutes. In order to provide for 
this, the doughs following the first are set at a lower tempera¬ 
ture, or possibly with less yeast, so as to come on rather more 
slowly. A good deal of the art of the baker consists in so ad¬ 
justing these conditions as to ensure that all doughs shall be 
just lipe when taken, notwithstanding that they have had to 
lie for different lengths of time. No general rule can be laid 
down for this. The only thing is to note the extent to which 
the speed of working of a dough is affected by variations in the 
factors which the baker has under his control, and modify 
these accordingly. After all, experience is the great factor 
here, and this can only be gained by watching the best prac¬ 
tice in the bakery. 

The initial temperature is governed fairly easily, but how 
about changes during the time of fermentation? The condi¬ 
tions are altogether different in the winter and the summer 
time. With a high bake shop temperature the dough has a 
tendency to ‘'run away,” because it gets wanned up unduly by 
the hot bakehouse. Conversely, in winter the dough is starved 
by the cold surrounding air. The remedies for these troubles 
are twofold in character. First of all one tries to eliminate the 
effect of extremes in outside temperature. In summer the en¬ 
deavor is made to secure coolness by ventilation, and possibly 
by cooling—^by the action of ice or otherwise—the incoming 
air. In winter the bakery is kept as warm as possible and the 
doughs are protected to the utmost possible extent from the 

98 




BREAD-SHOP PRACTICE 


chills and draughts by which they may be assailed. The pre¬ 
ceding represents one method of dealing with the problem. 
Another is to set the doughs cooler in summer and warmer in 
winter. It is thus hoped by varying the temperature to com¬ 
pensate the disturbing influences of outside extremes of heat 
or cold. It is scarcely possible to lay down any fixed rule in 
this matter. Again experience is the chief teacher. The only 
thing is to pay heed to her lessons, otherwise she keeps a 
frightfully dear school. 

Summaiy. 

Effect of temperature on fermentation of dough. When is 
a fermenting dough *Teady”? Experimental test on changes 
during dough fermentation. Time when dough is at its best 
condition. Dough fermentation has other objects than the 
aeration of dough. 

How is time of readiness determined? Bakery and other 
methods. 

Conditions affecting speed of fermentation. 

Temperature is therefore all important in the matter of 
dough fermentation. There are various factors by which the 
baker controls both temperature and fermentation. 






/ 



■A 


CHAPTER VIII 

BACTERIAL BREAD-MAKING TROUBLES 

“Sour Bread” as Understood by the Baker. 

If the student turns back to the last chapter and the life 
history it gives of a fermenting dough, he will find it stated 
that when over-fermented the bread commences to be sour in 
taste, which property is accentuated as fermentation is con¬ 
tinued. The reason wdiy bread should go sour requires at this 
stage some little explanation. We are landed back again to 
the chemistry of minute forms of life. It has been already de¬ 
scribed how yeast in its life functions decomposes sugar into 
alcohol and carbon dioxide gas. Tliere are other very small 
organisms that produce equally definite, but quite different, 
changes. Thus one such organism attacks some forms of 
sugar and converts them into acid known as lactic acid. When 
milk goes sour, it is because the organisms refeiTed to have 
decomposed the sugar of milk into lactic acid. 

Some little description of the nature of these organisms is 
necessary. And it is difficult to give this description without 
using purely technical terms, as there are no popular descrip¬ 
tive names of these organisms. They are included in a group 
known as Schizomycetes or splitting fungi. They are minute 
plants consisting of a single cell. They multiply by a system 
of fission or splitting, and in addition form spores or seeds 
which are extremely tenacious of life. In actual size the 
schizomycetes are considerably smaller than yeast cells. While 
the latter have a diameter of 8 to 9 mkms, the former are 
about 1.5 to 2.0 mkms in length. Among the schizomycetes 
are two groups known respectively as bacteria and bacilli, 
which names are more familiar to the general reader. Of the 
numerous members of this family, many assume shapes so 
similar that any differentiation by microscopic examination is 
very difficult. Further, while certain such organisms produce 
a definite chemical change in substances, there is a difficulty in 
classification because distinct organisms may under certain 
conditions produce the same chemical change. For our present 


100 


BREAD-SHOP PRACTICE 


purpose, however, we may take a classification based on the 
chemical changes produced and accordingly select a few of the 
more important to the baker. 

Bacterium Termo. This is essentially the organism of 
putrefaction. When meat juice, malt-wort, and other liquids 
are exposed to air they become charged with this organism 
and putrefaction readily occurs. In previously putrefying 
liquids, these bacteria have grown and multiplied, then their 
spores escape into the air, and in turn, when sown into a liquid 
capable of supporting their life, they speedily commence an 
active existence and produce the series of changes which we 
speak of generically as putrefaction. The processes of preserv¬ 
ing fruit, meat, etc., by canning depends on heating the con¬ 
tents of each can to such a temperature that all spores or 
germs of bacteria are completely destroyed, and then sealing 
down so as to prevent the entry of fresh spores. When such 
cases are opened and their contents exposed to the atmosphere, 
spores of bacterium termo find their way in and set up putre¬ 
faction. 

BadUi. These are a group of schizomycetes in which the 
cells are elongated and grow end to end to form a stick or rod, 
which the word bacillus literally means. Bacillus subtilis is 
one of this group, and in common with bacterium termo is 
most active in causing putrefaction. 

Bacterium. lactis. This is essentially the organism to which 
reference has already been made, by which the sugar of milk 
is converted into lactic acid and so milk becomes sour. Several 
organisms possess this power, and transform also ordinary glu¬ 
cose and maltose into the same acid. Lactic acid fermentation 
takes place most favorably at a temperature of 35 degrees C., 
and therefore those who wish to utilize alcohol fermentation 
adopt a temperature of about 25 degrees C., at which yeast 
functions vigorously, but bacterium lactis is comparatively 
inert. 

Butyric fermentation. There is yet another bacterial fer¬ 
mentation by which lactic acid is converted into butyiic acid, 
which latter body has the characteristic smell of rancid butter. 
Several bacteria are capable of producing butyric acid. 


101 




• BREAD-SHOP PRACTICE 


Acetic fermentation. Certain organisms possess the power 
of changing wine and beer into vinegar. Their action is es¬ 
sentially one in which the alcohol is oxidized into acetic acid. 

Viscous fermentation. Certain organisms possess the 
power of attacking beer, and changing it into a viscous liquid 
which runs from the tap in a thick stream. A somewhat anal¬ 
ogous change may be produced in bread, which is then known 
as **ropy’^ bread, to which further reference will be made. The 
ropy condition in bread is regarded as being due to the pres¬ 
ence of a specific organism known as Bacillus mesentericus 
fuscus. 

Activity of These Bacteria Dependent on Yeast. 

Speaking generally when any of the above organisms are 
present in dough, and the conditions are favorable for their 
development and activity, then the troubles of sour or ropy 
bread occur. It has been already mentioned incidentally that 
yeast is a wasteful feeder; and why it should break up such 
enormous quantities of sugar into alcohol and carbon dioxide 
gas for the sake of the very small proportion that it actually 
assimilates has long been a puzzle to scientists. Some very 
important contributions to the study of this subject were made 
in the early part of the century by Gennan brewing chemists. 
Delbruck dealt with these very fully in a lecture delivered be¬ 
fore the English Institute of Brewing in 1906. He pointed out 
that in the feiTnentation energy of yeast lay its most powerful 
defensive agency against the attacks and encroachments of 
foreign organisms. Yeast by sending out such large quantities 
of carbon dioxide and alcohol thus protected itself against all 
the organisms for which these substances are poisonous. The 
effect of the carbon dioxide is ten times as deadly as that of the 
alcohol. (May this be regarded as a subtle intimation of the 
relative toxicity of aerated waters and whisky?) This sugar 
decomposition by yeast may be regarded as a part of its fight¬ 
ing organization, and the law that in the struggle for exis¬ 
tence those organisms which specialized in the production of 
fighting substances would be the strongest applies especially 
to the micro-organisms. Granted, therefore, a dough contain¬ 
ing other micro-organisms than yeast, a vigorous yeast fer- 


102 






BREAD-SHOP PRACTICE 


mentation is one of the best specifics against the development 
of the acid-producing bacteria. This finds substantial corrob¬ 
oration in practice, since, while yeast fermentation is healthy 
and vigorous, acid production is held in abeyance. It is only 
when the action of the yeast is sickly and weak that the great¬ 
est danger of the production of sour bread arises. 

How Are These Organisms Introduced? 

At this stage the question may fairly be asked: "‘How do 
these undesirable organisms find their way into the dough?” 
At one time there can be no doubt that yeast was largely con¬ 
taminated with foreign organisms, and much of Pasteur’s his¬ 
toric work was do^e in the direction of showing the harm thus 
caused, and how *it might be prevented by securing a pure 
yeast. Now, however, yeast as offered to the baker is practi¬ 
cally free from any foreign organisms. Flour can not be so 
readily purified and may contain a dangerous quantity of micro¬ 
organisms. These find a lodgment on the outer surface of the 
grain, and during the act of milling may be rubbed off into 
the flour. But the freer the grain is from branny particles the 
freer it also is from these organisms, and the less tendency is 
there for the resultant bread to be sour. This is well exempli¬ 
fied by the following test: As a No. 1 sample, 15 pounds of 
spring American patent flour was taken, for No. 2 a mixture 
was made of 12 pounds spring American baker’s grade and 3 
pounds of low grade (red dog) flour. Both were fermented in 
precisely the same manner and with the same proportions of 
yeast, etc. At the end of three and one-half hours a loaf was 
baked from each. That from the white flour had a total acidity 
• of 0.477 per cent, and that from the darker mixture was 1.140 
per cent. In order to obtain a pure flour, millers now carefully 
wash before milling any wheats that are not in themselves 
scrupulously clean. Not only does this remove extraneous 
dirt, but it also removes extraneous organisms. Clean wheat 
and bran-free flour are the miller’s contributions to sweet and 
healthy bread. 

Effect of Temperature and Slack Doughs. 

Again we come back to the dough temperature question; 
many of these disease ferments, as the acid-producing and 


103 





BREAD-SHOP PRACTICE 


other analogous organisms, thrive and develop best at a com¬ 
paratively high temperature, and by careful selection a 
temperature can be employed which pennits yeast to work 
vigorously while the disease ferments are held dormant. 
Some years ago more importance was attached to this 
point than at present. Thus at a temperature of 25 de¬ 
grees C. it was believed that yeast could work well but that 
the lactic acid organism, for example, was comparatively inac¬ 
tive. But with a temperature of 35 degrees C., not only yeast 
but these other organisms got into full swing. Gradually the 
longer methods of fermentation, with comparatively cool 
doughs, were replaced by quicker and shorter methods. With ’ 
these latter the doughs were set hotter, and the question arose 
whether there was relatively a greater proportion of acid 
formed during fermentation. 

High temperatures are among the means of accelerating 
the course of fermentation as a whole, and consequently with 
such temperatures, everything else being equal, the sour stage 
is reached at a less time from the start than if the dough is 
worked at a lower temperature. The crucial point is, whether 
for the same amount of carbon dioxide gas evolved during fer¬ 
mentation there is more acid produced at a high temperature 
than at a low one. If the answer to this inquiry be in the nega¬ 
tive then with feimentation being arrested at the same stage 
of its progress there is no more danger of bread worked warm 
becoming sour than that which is worked cool. In order to 
throw light on this point the following experiments were 
made: 

Mixtures were prepared of 50 parts flour, 200 parts water 
and 2.5 parts compressed yeast. The mixtures were placed in 
a yeast-testing apparatus by means of which they could be 
kept at a desired temperature, and the quantity of gas 
evolved measured. The temperatures selected were 75 degrees 
and 95 degrees Fahr., respectively, at which they were main¬ 
tained until the same volume of gas (in this case 350 c.c.) had • 
been evolved in each experiment. In duplicate mixtures the 
acidity was determined as soon as made up, and that of the 
fermented mixtures as soon as the standard volume of gas 
had been evolved. There was each time an increase, and on 


104 




BREAD-SHOP PRACTICE 


subtracting the initial quantity from that of the close the 
amount produced during fermentation was ascertained. In 
another experiment the fermenting mixture was first main¬ 
tained at 95 degrees Fahr., until 175 c.c. of gas had been 
evolved; it was then cooled to 75 degrees Fahr. and kept at 
that temperature until 90 c.c. more had come over. The 
temperature was then again raised, and maintained at 95 de¬ 
grees Fahr. until the whole 350 c.c. of gas had been evolved. 
The following table gives the time required for the evolution 
of 350 c.c. of gas, and the amount of acidity produced during 
fermentation reckoned in each case as lactic acid: 

Acid produced 
Time taken during 
hours, fermentation. 


Working at 75° Fahr. 10^ 0.219 

Working at 95° Fahr. 35^ 0.115 

Repeats— 

Working at 75° Fahr. Iiy 2 0.225 

Working at 95° Fahr. 0.180 

Working partly at 75° Fahr., and partly 

at 95° Fahr., as above described. 7^A 0.180 


Now these tests and also the practical experience of the 
bakery go to show that for the same amount of alcoholic fer¬ 
mentation and production of carbon dioxide gas, a compara¬ 
tively high temperature is at least not more productive of 
acidity than a much lower one. This has a very important 
bearing on the question of the employment of short systems 
of fermentation, which have now largely replaced the older 
long systems. 

In passing one point must not be forgotten, and that is 
that with a short system, the same amount of time of over¬ 
working is much more serious than with a long one. Thus 
in the 75 degree tests an extra hour means only about 9 per 
cent too much fermentation, while at the higher temperature 
it means about 26 per cent. That is to say, the excess of fer¬ 
mentation is practically three times as much in the latter case 
as the former. Putting it another way, five minutes too much 
at 95 degrees will do as much harm as a quarter of an hour 
at 75 degrees Fahr. The obvious moral is that in all short 


105 








BREAD-SHOP PRACTICE 


working systems times must be watched and doughs taken 
with the utmost exactitude. The last experiment recorded 
was made with the object of determining whether a sudden 
lowering of temperature during fermentation (such as might 
be produced by a sharp chill) had a tendency to increase acid¬ 
ity, The results show that no such increase was caused in 
this instance. 

Lactic, Acetic and Butyric Acids. 

So far no reference has been made to any differentiation 
of acids in sour bread, but mention has been made in dealing 
with the acid-producing bacteria of the following acids: Lactic, 
acetic and butyric acids. Of these, lactic acid is a compara¬ 
tively fixed acid, its boiling point is higher than that of water, 
although when a mixture of lactic acid and water is boiled a 
certain amount of acid volatilizes with the steam. There re¬ 
mains behind, however, a thick, syrupy liquid, which at a tem¬ 
perature of 130 degrees C. (266 degrees Fahr.) commences 
to decompose with the evolution of water. Lactic acid is quite 
odorless, so that the characteristic smell of sour milk is not 
due to the lactic acid present. Naturally, therefore, the sour 
taste of sour bread may be caused by lactic acid, but its sour 
smell must be due to the presence of some other substance. 

In its concentrated form acetic acid has a pungent and 
very characteristic smell, which is that which gives vinegar 
its special qualities. It boils at 244 degrees Fahr. Butyric 
acid has a smell recalling that of rancid butter superposed on 
that of acetic acid. Its boiling point is high (324 degrees 
Fahr.) but it is sufficiently volatile to make its presence known 
at ordinary temperatures by its extremely penetrating and 
persistent odor, which is intensely disagreeable. The fact 
that lactic acid is odorless, and that acetic and butyric acids 
smell strongly at ordinary tempei*atures, has led to the latter 
being called the volatile acids of sour bread. 

Space will not permit a description of the methods of de¬ 
termining the actual amount of each acid in sour bread; but 
speaking generally, lactic acid is that first produced, and 
within limits may be regarded as a normal constituent of per¬ 
fectly sweet bread. Acetic acid is that next produced, and 


106 



BREAD-SHOP PRACTICE 


finally, in extreme cases, buytric acid, which is also accom¬ 
panied by other products of putrefaction. The acidity of 
bread may be divided among the various acids in approxi¬ 
mately the following proportions: 


Lactic acid.about 95 per cent 

Acetic acid.about 5 per cent 

Butyric acid.from 0.0 to about 0.5 per cent 


It is the conditions which lead to the production of excess 
of these which the baker has to learn and provide against in 
order to prevent sourness. The following is a brief statement 
of the essential causes of the production of sour bread. 

Causes of Sour Bread. 

1. “Sour bread,” as understood by the baker, is the result 
of a combination of bacterial fennentations. Principal among 
these is that producing lactic acid, which constitutes about 95 
per cent of the total acidity. The remainder is due to acetic 
acid, with, in very bad cases, traces of butyric acid. In addi¬ 
tion to the development of acidity, sour—as distinct from acid 
—bread shows signs of putrefactive decomposition. 

2. The acid and putrefactive fermentations are produced 
by bacteria to be found in the dough. 

3. These bacteria may be introduced by the yeast, by the 
use of dirty vessels, and by the flour; but their presence in the 
flour is the most general cause of “sourness,” and the lower 
the grade of the flour, the greater is the risk of sour bread. 

4. The activity of these bacteria is dependent on that of 
the yeast; while the latter is active, the bacteria are compar¬ 
atively quiescent. With the exhaustion of the yeast, or cessa¬ 
tion of active fermentation through the assimilation of all fer¬ 
mentable material, a stage is attained in bread fermentation 
when bacteria are excessively active, and sourness rapidly de¬ 
velops. 

5. Temperature and slackness of dough have but little 
effect on sourness, except that indirectly they affect the speed 
of the whole course of fermentation, and so hasten or retard 
the arrival of the bacterial fermentation stage. This stage 
being reached, the production of sourness is accelerated by 
both high temperature and slackness of dough. 


107 








BREAD-SHOP PRACTICE 


6. Exposure to air has no appreciable effect on sourness, 
and may even through its cooling action be beneficial. 

* 7. The two principal causes of sourness are: Allowing the 
fermentation to proceed beyond the normal into the souring 
stage; and the use of materials or vessels containing abnormal¬ 
ly high proportions of bacteria, especially when employed with 
weak and inactive yeasts. 

Rope in Bread. 

Sour bread as just described and dealt with is one of the 
great enemies of the baker. But a more insidious, and far 
more dreaded foe, is that colloquially known as “rope.” Prob¬ 
ably all bakers have heard of it, some have seen it, and others 
are thankful that it has never come within their personal ex¬ 
perience. Reference was made in the earlier part of this 
chapter to ropiness under the heading “Viscous Fermentation,” 
and its association with an organism of the bacillus type 

t 

known as bacillus mesentericus fuscus. 

Experimenting in the Production of Rope. 

To produce rope in bread in a bakery is about as criminal 
and foolish as to start smoking in a powder magazine. But 
there are things which are permissible in a detached scientific 
laboratory that could not be tolerated in the bakeshop. Here 
perhaps the bakery student may have an opportunity of study¬ 
ing rope at first hand. In the first place he should get some 
low-grade flour, having a fair amount of branny particles pres¬ 
ent. This may be ordinary red dog flour. From this let him 
make and bake a loaf, using only flour, salt, yeast, and water. 
The dough should be made up slack, not allowed to overwork, 
and then baked in a comparatively cool oven, so as to produce 
a rather sodden, clammy loaf. A very convenient size is a loaf 
of about eight ounces, baked in a tin. So far, this may be 
done in the bakery. Then the loaf should be taken to the 
laboratory and placed in a biological incubating oven, main¬ 
tained at a temperature of 38 degrees C. A useful substitute 
for this may be improvised from an ordinary chemical hot 
water oven, the temperature being regulated by adjusting the 
flame of the burner. The loaf should be wi’apped in successive 
pieces of wetted parchment paper before being placed in the 


108 





BREAD-SHOP PRACTICE 


oven. A beaker or dish of water should also be put in the oven, 
and replenished as the water evaporates. The object is to keep 
the loaf moist and warm. In two days take it out, and cut 
it in two. The interior may be quite sweet and apparently 
unchanged, or it may evolve a peculiar smell, and brownish 
moist spots may have commenced to develop. In any case, ' 
wet the surfaces of the cut pieces at once, place them together, 
wrap up as before in wet paper and return to the oven. Exam¬ 
ine again on the third day, and in the absence of any dedded 
change continue the incubation until the fourth day. By this 
time, in all probability, the dark spots will have developed still 
further, and the substance of the bread will have changed 
locally to a thick gummy mass. On touching this with a glass 
rod, a stringy fibre may be drawn out, hence the name rope. 

A most nauseating odor of a very characteristic t 5 rpe is at the 
same time developed. It is safe to say that this, when once 
smelled by a baker, is never forgotten. 

Of course, on the other hand, there may be a total failure 
to get these characteristic changes—a result of the absence 
of the rope organism from the bread. With flour of this kind 
the writer’s own experience is that rope very rarely fails to 
develop. Assuming that the student’s experiment follows the 
general rule of the writer’s observation, let him examine the 
infected loaf somewhat closely. He will find that the develop¬ 
ment of rope proceeds from the center of the loaf, and not 
from the outside, showing that the infecting organism is con¬ 
tained in the dough itself and does not usually enter from 
without. 

If the student has the good fortune to be able to work in a 
bacteriological laboratory, his teacher will guide him in fur¬ 
ther experiments in the direction of sowing some of this ropy 
matter in a suitable medium, and thus isolating the infecting 
organism. Such w^ork is, however, of a very special character, 
and can not be carried out by the ordinary baker student with¬ 
out assistance of this kind. 

Bi’anny Flours Most Liable to Rope. 

If wished, several flours may be examined by baking and 
subsequent incubation in this manner. Generally speaking. 


109 





BREAD-SHOP PRACTICE 


the higher grade flours are less liable to the generation of 
rope than the lower qualities. In fact, the liability to rope 
follows very closely the proportion of branny matter present. 
It is not a difficult deduction to make from this that rope 
infection is due to some substance or body adhering to the 
outside of the grain, and not to anything which is contained in 
the interior. That adherent outside body is now regarded as 
being the rope bacillus. From this it is easy to formulate a 
working theory as to the cause of rope, viz., that some wheats 
get infected with the bacillus on the outside of the skin. Then, 
when ground into flour, any branny particles of the wheat 
convey the bacillus into the flour with them, and so make it 
ropy. 

Other Causes of Rope. 

It may very naturally be said this does not cover the 
whole of rope possibilities, since rope is sometimes known with 
the very finest dressed flours, in which not a particle of bran 
can be seen. Still, in cases such as these, the probability is 
that the rope bacillus was present in large amount on the out¬ 
side of the grain, and has been rubbed off or otherwise trans^ 
ferred from the bran to the flour during the operations of 
milling. In such cases an examination of the bran itself, if 
possible, would be illuminating. 

We have indicated one almost certain cause of rope, viz., 
infected flour, and that can be still further investigated by the 
baking and incubation method described. If a flour be taken 
which is normally free from rope, and samples of bran added, 
and then the test carried out as before, infected bran \rtll set 
up rope in the test loaves. 

There seems no doubt that when potatoes were largely 
used in bread-making they were also a possible source of rope 
infection. This may also be tested in the same manner. If 
pieces of raw unwashed potato peelings are added to pure flour, 
and tested by baking and incubation as before, they will often 
set up rope in the loaf. Of course all potatoes are not similarly 
infected. 

There is another very important experiment that may well 
be made in the way just described, and that is to deteiTnine 




110 





BREAD-SHOP PRACTICE 


whether or no the yeast is a source of rope infection. If yeast 
is the cause, then a loaf made without yeast should be free 
from rope. If one of the flours baked has been specially ropy, 
let that one be selected and aerated by the addition of soda 
bicarbonate and either tartaric acid or acid calcium phosphate. 
In apportioning the soda and acid, it is very well worth while 
to bake two separate loaves. In the first one, take such an 
amount of soda as will be in slight but definite excess over the 
acid. 

(The student who has been learning the chemistry side of 
baldng will know quite well how to do this; it may, however, 
be well to place the method on record here. Assuming the 
accessibility of a sensitive balance, weigh off 1 gram of soda, 
transfer to a beaker and dissolve in cold water. Next weigh 
off accurately 5 grams of tartaric acid. Add one or two drops 
of methyl orange solution to the soda, which will then be tinted 
yellow. Add tartaric acid, little by little, from the weighed 
portion, and stir till all action is over. Each addition slightly 
reddens the soda solution at the point of contact. CJontinue 
this until the last addition leaves the solution of an orange 
tint—^intermediate between the yellow when there is an excess 
of soda and the red when there is an excess of acid. At this 
stage the soda and acid are just equivalent to each other and 
the solution is said to be neutral. Weigh the amount of acid 
remaining, and subtract from the original figure of 5 grams; 
the difference is the amount actually used. As a guide it may 
be mentioned that 1.0 part of pure soda requires to neutralize 
it 0.893 part of pure tartaric acid.) 

Acidity Inimical to Rope Development. 

In making the first or soda-in-excess test, take nine-tenths 
of the neutralizing quantity of acid; that is, if both bodies were 
quite pure, for every gram of soda, 0.893 — 0.089 = 0.804 
gram of tartaric acid. In this case there is a 10 per cent 
deficiency in acid. In the second test take a 10 per cent excess 
of acid, that is, an additional tenth of acid to that required 
for the production of neutrality. Again, with the pure mate¬ 
rials this is 0.893 4 - 0.089 = 0.982 gram of acid to each gram 
of soda. Do not forget that in the actual test the variations 


111 





BREAD-SHOP PRACTICE 


must be based on the actual quantity of acid required for 
neutralization. Made in this way, No. 1 has a definite alkaline, 
and No. 2 a definite acid, reaction. Complete the tests. No. 
1 will show rope quite as quickly as in a loaf baked with yeast. 
This goes to prove that yeast is not the cause of rope in the 
particular case; and with modern yeasts it may be laid down 
as a general rule that it is very unlikely that yeast causes 
the diseased condition. 

The rope bacillus is in fact an organism whose natural 
habitat is the soil, and hence wheat, and potatoes, which are 
direct products of the earth, are exposed to this contamination. 
Yeast from its very mode of manufacture is exceedingly un¬ 
likely to be infected with soil organisms. 

The second, or acid, reacting loaf will not show rope any¬ 
thing like so readily, and may in fact escape the trouble al¬ 
together. The reaspn for this immunity will be discussed a 
little later. 

A remark may here be interposed in passing. If the student 
should seek the assistance of a bacteriological chemist in mak¬ 
ing these expeiiments such a chemist might very well say, on 
reading the directions here given: “But the methods sug¬ 
gested do not guarantee actual sterilization nor complete 
exclusion of foreign organisms during the course of the experi¬ 
ments.” This would be quite a fair criticism, but the condi¬ 
tions are after all much more exacting than occur in the 
bakery, and if rope does develop in experiments made in this 
fashion, it is far more probable that it would do so with actual 
' bake shop surroundings. One is always a little puzzled in 
giving directions for carrying out a scientific test by a baker 
student. If rigid scientific accuracy is demanded and incul¬ 
cated, the test becomes so difficult that the student for whom 
one is catering could not possibly carry it out. If these con¬ 
ditions are somewhat relaxed, the results obtained are not 
absolutely conclusive. The only thing is to strike a happy 
mean, which will make the tests possible and at the same 
time make them in all probability reasonably accurate. In 
view of this element of uncertainty the student should remem¬ 
ber that his tests are not necessarily of the nature of absolute 
proofs, but only repetitions of scientific tests with some pre- 


112 



BREAD-SHOP PRACTICE 


cautions dispensed with in order to render them possible of 
performance by him. 

How Rope Develops in an Ordinary Bakerj\ 

If the student has learned, in the manner described, the 
nature and properties of rope in bread, he will be quite able 
to recognize it, should it unfortunately occur in any bakery 
with which he may be connected. It is during hot weather 
that an outbreak of rope is much more likely to occur. When 
cut in the ordinary manner, when say about twenty-four hours 
old, the loaf is observed to have a faint sickly smell, and on 
being placed on one side soon develops all the characteristics 
properties. Brown spots are observed to form; these may be 
drawn out into long threads, and the intense valerian-like odor 
of rope is evolved by the bread. 

Watkins’s Researches. 

Watkins has examined rope and its causes very carefully 
and has published his results in a paper read before the Society 
of Chemical Industry. His experiments were first directed to 
prove that the diseased portions of an infected loaf could easily 
impart the same trouble to sound materials. Then if a little 
of the ropy matter is sowed in nutrient gelatin (a sterilized 
jelly) it reproduces and sets up rope therein. By appropriate 
cultivation in this way a fairly pure culture of the rope bacillus 
is obtainable. Also, on adding a little ropy matter to sound 
bread, and to sound flour which was then baked, ropiness was 
in each case induced by incubation at a temperature of from 
25 degrees to 30 degrees C. in a moist atmosphere. On the 
other hand parts of the same loaves kept at a temperature of 
below 18 degrees C., whether in a dryer or an excessively moist 
atmosphere, showed no signs of the development of rope. This 
temperature experiment was checked in many ways, and the 
following definite conclusion was arrived at by Watkins: '‘Ele¬ 
vated temperature appears to be absolutely necessary to the 
development of ropiness in bread. Even when the bacillus is 
present in large numbers, moisture alone, when the temperar 
ture is low, is incapable of causing its appearance.” 

Watkins further pointed out that 0.1 per cent of acetic acid 
in bread inhibited the growth and development of rope. This 


113 





BREAD-SHOP PRACTICE 


amount is about 0.2 pounds to the barrel (196 pounds of flour), 
and 0.2 pounds equals just over 3 ounces. This quantity is 
not prejudicial to the quality of the bread, and is recommended 
as a remedy by Watkins. 

Another important point insisted on by him was the very 
marked resistance by the rope bacillus to the effects of heat. 
Thus when an active culture was raised to boiling water heat 
on three successive days, and then used in the dough of a 
trial loaf which was baked for fortj' minutes, it rapidly de¬ 
veloped rope in the resultant bread. Watkins therefore drew 
the conclusion that it is hopeless for the baker to endeavor to 
prevent the disease by extra long baking in order to destroy 
the bacillus. 

Flour Practically Always Source of Infection. 

Coming to the more immediately direct question of the 
baker. How does my bread get infected with rope? Watkins' 
reply is that in modern practice the flour is the only material 
responsible for the appearance of this disease. As among the 
reasons for his coming to this conclusion he points out that 
the remedies commonly advocated for its cure, such as a 
thorough cleaning and disinfection of the bakery and all 
utensils, have frequently proved inadequate. On the other 
hand, he has found that a complete change of flour has in 
more than one case resulted in the absolute disappearance of 
the disease. In very bad cases of rope infection he has found 
by a series of tests which of a number of flours is the infec¬ 
tious one, and on its removal the disease has ceased to give 
any trouble. 

Testing Flour for Rope. 

All this evidence in favor of the flour being the culprit has 
led him in case of rope trouble to urge the testing of the vari¬ 
ous flours used for rope. The little baking and incubation 
test already described may be used for that purpose. And 
where rope is unfortunately already in the bakery, there is 
not the same objection to making these tests as where no 
such trouble exists. The tests may be made therefore in such 
case by the baker himself, in the bakery. The following pre¬ 
cautions may be taken: First, bake all tins and other utensils 


114 





BREAD-SHOP PRACTICE 


(mixing bowls, etc.) in a hot oven for an hour to sterilize them 
thoroughly. Wash the hands with extreme care, use water, 
yeast and salt that are free from contamination. Take the 
flour from each variety in stock, and make the test with all 
possible precautions to avoid infection. To be absolutely sure, 
the dough making, etc., may be done in the open air, and the 
materials taken from some source outside the bake shop. In 
other words, use nothing if possible which has ever been in 
the bake shop, and thus avoid any general contamination. As 
an additional precaution, overalls may well be worn to prevent 
infection from clothing worn in the bakery. Having thus made 
an absolutely pure dough it may be covered over with a steril¬ 
ized (baked) piece of linen or cotton material and taken to the 
oven. The cover is then removed and the loaf baked (under¬ 
baked rather than over). It may again be covered over, taken 
outside and wrapped in parchment paper as before, brought 
into the bakery and placed in a prover, where it is subjected 
to a damp heat of 25 to 30 degrees C. The loaf may be cut 
and examined at the end of twenty-four hours. A ropy flour 
will by that time show the characteristic signs, while a sound 
flour will have given no rope reaction. The bread may be 
again wrapped up in the paper and returned to the prover for 
another twenty-four hours. If, at the end of that time, it is 
still sound, the flour may be passed as free from rope. 

Watkins suggests the following as his method of testing 
flour for rope by either the miller or baker: Take a series 
of ten ordinary glass test tubes (6 by 1 inches), wash them, 
boil in water for an hour, rinse with clean direct tap water, 
and drain. Then bake in a thoroughly hot baker’s oven (450 
degrees Fahr.) for three hours in order to completely sterilize 
them. Take out and allow to cool in the open. Place in each 
tube a finger of bread 3 inches by i/o inch byV2 inch, cut from 
the center of the same two-day-old loaf. (These pieces will 
weigh each about 5 grams.) Moisten each piece with 6 c. c. 
of recently boiled distilled water, then plug all the tubes with 
cotton wool which has been previously sterilized by baking to 
a very light brown tint. Sterilize the tubes and their contents 
by immersion in boiling water for an hour on three successive 

days. 


115 




BREAD-SHOP PRACTICE 


These tubes are conveniently prepared in batches a few 
days previous to being required. In order to carry out a test 
take 2 grams of the sample of flour to be examined and mix 
in a beaker with 100 c. c. of distilled water (there is no objec¬ 
tion to directly drawn pure tap water). Place the beaker 
containing the mixture in a boiling water bath for 30 minutes. 
This treatment will destroy most other organisms present in 
flour except the rope bacillus, etc. Take seven of the prepared 
tubes and, preferably working in the open, remove the plugs 
and add 1 to 7 cubic centimeters of the boiled flour mixture. 
Re-plug immediately. Keep the other remaining tubes to 
serve as checks. Place the whole series in an incubator or 
in the bakery in a prover so as to maintain them at a tempera¬ 
ture of 20 to 30 degrees C. (the writer sees no objection to 
the temperature reaching even 35 degrees C.). At the end of 
twenty-four hours, examine the 'contents of each tube for 
both the smell and appearance of ropiness. If present, the 
whole of the tubes will usually show signs of it. Naturally 
the greater the amount of flour mixture added the greater is 
likely to be the development of rope. In any case, the check 
tubes must remain sound or the experiment must be rejected. 
It is well to continue the test another twenty-four hours, and 
if at the end of that time there is no indication of ropiness 
the flour may be passed as sound. 

Of the two tests, the baker will probably find that of direct 
baking of the suspected flour on the whole more convement 
for him and more in line with his usual methods. By either 
method, ropy flour should however be identified. 

Watkins's was a most valuable contribution to the subject 
of rope in bread, but there are certain additional points one 
would like to have seen dealt with. For example, his experi¬ 
ments would have been more complete had they included in¬ 
vestigations as to how far the development of ropiness was 
governed by the comparative moistness of bread at tempera¬ 
tures just a little higher than the lower limit of activity of 
the rope bacillus. Now, below 18 degrees C. (64 degrees Fahr.) 
the presence of moisture does not cause the development of 
ropiness. The problem is, what effect has excess of moisture 
at higher temperature, say 20 degrees C. and over ? Probably 


116 





BREAD-SHOP PRACTICE 


there would be a more rapid development in the moister loaf. 
Watkins refers to the generally given advice that prolonged 
baking should be given when using a flour suspected of rope, 
and discounts it because the longer baking will not destroy the 
rope bacillus as a result of the effect of heat. Such recom¬ 
mendations, were in most cases based not on the likelihood of 
being able to kill the rope organism, but rather with the object 
of making the bread drier, and thus a less favorable medium 
for the spread of the disease. 

Why Cleaning and Sterihzing Are Advocated. 

The great thing here is the definite tracing of the original 
source of rope to the flour as the channel of introduction. But 
rope having once got into the dough, it is simply a question 
of a comparatively short time for it to permeate troughs and 
other utensils. This having happened, or in view of the im¬ 
minence of its happening, the whole of the advocated precau¬ 
tions for cleaning and sterilizing these have all the force and 
necessity which have been attributed to them. 

Another untoward property of the rope bacillus is that it 
readily forms spores, and a bakery is a place in which from its 
nature and character spores are readily liberated and dissem- . 
inated through the atmosphere. It is necessary to bear this in 
mind because there are at times cases of rope which it is almost 
impossible to explain otherwise than by the theory of aerial 
infection. As illustrations, it may be mentioned that some¬ 
times a complete change of flour has not cured the disease. 
Further, one miller’s flour may be used in one bakery where 
rope is prevalent, and also in another in which perfectly sound 
bread is being obtained. Hence the necessity of thoroughly 
cleaning and sterilizing the entire building in a case of per¬ 
sistent rope. 

Precautions for the Miller. 

Having dealt thus fully with the nature and properties of 
rope, its prevention and cure in actual practice are of the 
utmost importance. 

First of all, the miller as the purveyor of the raw material 
can be of great help. As a part of the routine of mill testing, 
especially in the hot season, the wheat itself might very well 


117 




BREAD-SHOP PRACTICE 




be tested. This is very easily done by shaking up a few grains 
with warm water and testing the water by a slight modifica¬ 
tion of Watkins’s test. In just the same way as with flour, 
the washing water should be heated so as to destroy most 
other commonly present organisms, and then used to inoculate 
the sterilized fingers of bread just as in testing flour. In any 
cases where rope develops, a thorough wheat washing is one of 
the best remedies. Another is to set any such infected wheat 
aside and use it only in the cold season of the year. 

Regular S)"stem of Rope Tests. 

Coming to the bakery, a test for rope on every sample of 
flour on' its being received would entail a large amount of 
routine work that many bakers will grudge, feeling most likely 
that the risk is too small to warrant the trouble involved in 
making this systematic examination. This is where the en¬ 
thusiastic bakery student may be of seiwice. Let him volun¬ 
teer to make such tests during the summer months, explaining 
their object. In most instances his efforts in this direction will 
receive a welcome; and such tests being regularly made, and 
the results brought before his employer, will get to be looked 
for as a valuable paid: of the bake shop routine. Not only will 
he then be able to report on whether or no any flour is ropy, 
but also the freedom or otherwise of the flour and bread from 
other organisms will thus be shown. Thus he will be able to 
note whether or not the incubated loaves have a tendency to 
sourness. Also, they will indicate whether the flour is mouldy 
or musty. These tests have one great natural advantage. 
The results are not in the form of a senes of figures or per¬ 
centages, which do not appeal very strongly to many bakers of 
an older school, but are in the fonn of an actual object to be 
laid before the baker for his inspection. And that object is 
the one which of all others rivets the baker’s attention—a 
baked loaf. 

In making any such tests, for the reasons already given it 
is well to conduct them outside the bakery proper, so as to 
avoid infection of the actual bakery by any bad specimen. The 
incubated loaves should be destroyed when done with and 
never allowed to lie about in or near the bakery itself. Such 


118 





BREAD-SHOP PRACTICE 


a course of tests would be a benefit to the young student, first 
because it would be valuable practice and experience, second, 
because its importance would be appreciated by a progressive 
employer. 

Systematic Cleansing of Bakery. 

The next very important item of prevention in the bakery 
is that of systematic cleansing of all utensils, and the bakery 
building. The treatment of the latter must depend on the 
nature of its construction. But even the humblest bake shop 
can be thoroughly limewashed at frequent intervals. And 
note, the washing should be with lime, not ordinary whiting, 
which is the inert carbonate of lime. Good quicklime should 
be procured, slaked with water, and used as a wash when 
fresh. It is much improved for this purpose if some bisulphite 
of lime is mixed in with it so as to make the mixture smell 
strongly of burning sulphur (sulphur dioxide). It will also 
be necessary to use a little size to make an adherent wash. 
This wash should be liberally applied, and in particular well 
daubed in so as to fill all crevices in brick or timber work. Not 
only does this treatment act as a bactericide (bacteria de¬ 
stroyer) , but it also prevents any crannies becoming the har¬ 
boring places of flies and other insect pests. 

Examining a Ropy Loaf. 

The next question that arises is what is to be done should 
there be a complaint of a ropy loaf. The actual loaf itself 
should be obtained if possible, and carefully examined. In par¬ 
ticular it should be noted whether the rope trouble appears 
to have commenced in the intenor of the loaf, or whether it 
has penetrated from the outside. Should the loaf have been 
made from ropy flour, the centers of infection are usually in 
the middle, or scattered through the interior of the loaf. Rope 
will naturally start where there happens to be a bacillus, and 
where the bread is warmest and moistest. Should it happen 
that a sound loaf has been placed in a rope impregnated atmos¬ 
phere, then the rope trouble may be seen to have infiltrated 
through the cracks or breaks in the crust. In the latter event 
the attention of the consumer should be called to the fact, and 
the condition of the bread container carefully examined. In- 


119 







BREAD-SHOP PRACTICE 


structions for its proper cleansing' and sterilizing should be 
given. Pans should be scalded out and washed with a solution 
of bisulphite of lime. Wooden cupboards may very well be 
lime-washed, as was suggested for the treatment of the bakery 
interior. After examination the diseased loaf should be de¬ 
stroyed, and in no case allowed to lie about the bake shop or 
adjoining premises. 

If the appearance of the loaf points to infection of the flour 
used, or in fact this point is uncertain then an examination of 
all flour becomes imperative. Having identified the faulty one 
or ones, they should be separated and only sound flours used 
in the making of the bread. Meantime, the cleaning and 
sterilizing of the utensils and the bakery itself should be car¬ 
ried out thoroughly. For a few days, glacial acetic acid may 
be added to the dough at the rate of 3 ounces per barrel of 
flour. The concentrated acid is corrosive, and should not be 
allowed to touch the skin, so the weighed quantity can be 
added and stirred into the bulk of the doughing water. This 
will practically inhibit any development of rope while any of 
the bacilli remain about the troughs, etc. Then the dough 
should be made rather stiffer than usual and well baked, so 
as to get a comparatively dry loaf. The bread should be cooled 
as rapidly as possible and stored in a cool place. It is doubtful 
whether the active cooperation of the customer can be ob¬ 
tained, but if by any means he or she can be persuaded to 
store the bread in cool dry place (preferably a refrigerator or 
ice-chest), and eat it as quickly as practicable after baking, 
then even rope-infected bread will continue sweet, as with the 
cold and bacillus will remain inert. 

Disposal of Infected Flour. 

If near the approach of winter, the infected flour may be 
kept until the cold season sets in, when it may be used with 
safety. But in that case, bakery sterilization should follow 
after all has been used up. 

The problem is not quite so simple when the flour may not 
keep until cold weather has set in. There are two alternatives 
—either the flour may be used with the addition of acetic acid 
and the precaution already mentioned, or such flour could 


120 



BREAD-SHOP PRACTICE 


almost certainly be used in making plain, hard, dry biscuits, 
and would keep in them. No one ever sees a ropy biscuit. 
As an altemative the flour could be sold for sizing flour, pig 
feed, or any convenient purpose other than human food. A 
word may be said in passing as to the harmlessness of the 
rope organism in articles of food. When once developed, the 
effects are so repulsive that infected bread becomes uneatable; 
but its presence in the earlier stages, when incapable of de¬ 
tection by the smell or taste, does not in any known way 
render the bread injurious or objectionable as an article of 
diet. 

Prevalence of Dormant Rope. 

The fact is that the writer has more or less definitely ar¬ 
rived at the conclusion that dormant rope is present in bread 
to a far greater extent than is usually thought. The follow¬ 
ing incident which came under his personal notice is illus¬ 
trative, and he thinks of sufficient interest to warrant its being 
related here. In about 1910 certain English medical men 
issued a manifesto in which they demanded that there should 
be a standard for bread, the essence of which was that it should 
be made from flour ^‘containing at least 80 per cent of the 
whole wheat, including the germ and semolina.'' In com¬ 
menting on this in their 1911 edition of “The Technology of 
Bread Making" the authors remarked that “in summer time 
standard dough and bread will afford a peculiarly suitable 
environment for the development of ropiness in the presence of 
the rope organism. When standard bread is being made a keen 
lookout should therefore be kept for the first signs of the 
advent of this trouble." The accuracy of this prediction was 
not long in being verified. Bakers began to make standard 
bread in response to a demand from the public, and in turn 
ordered standard flour from the millers, who naturally did 
their best to supply the article requested. Shortly, complaints 
of rope were heard, and in the case in point resulted in an 
action at law. A baker ordered “standard flour" from a miller, 
and made bread from that supplied. This bread became ropy, 
and the baker sued the miller for damages caused to his trade 
by supplying flour infected with the lope organism. The bak¬ 
er's case was that he bought flour from the miller, and on bak- 


121 





BREAD-SHOP PRACTICE 


ing it into bread, in August, that bread became ropy and his 
trade suffered seriously. On discovering the trouble, the baker 
ordered flour from another miller and the rope ceased. So far 
there was a prima facia case that the miller’s flour was respon¬ 
sible for the rope. When the case was approaching the hear¬ 
ing stage, those responsible for the miller’s defense realized 
that when the rope trouble ceased the weather had become 
considerably cooler. They took certain steps the effect of 
which will appear in reading the following colloquy, which 
occurred during the hearing of the action. The baker had 
given evidence, and Counsel for the miller was cross-examin¬ 
ing, when the following questions were put: 

Counsel: Now, might not this rope trouble have been 
caused by something else other than the miller’s flour ? 

Baker: No. 

Counsel: Might not the presence of rope in the bakehouse 
or the very hot weather have been the cause? 

Baker: Certainly not. I say that it was the miller’s flour 
and that only which caused the rope. 

Counsel (producing a loaf): Examine that loaf, please, 
will you? (Baker examines.) It is in a very bad state, isn’t 
it? 

Baker: Very. 

' Counsel: And is just exactly like the bread you made 
from the miller’s flour in August last, only worse? 

Baker: Yes, I suppose so. 

Counsel (producing second loaf): And this is just as bad 
or worse than the other? 

Baker: Yes. 

Ck>unsel: Now, Mr. Baker, will it surprise you to learn 
that both these loaves were purchased at your own shop dur¬ 
ing the last week? 

Baker: I shall be very much surprised. 

Counsel: And that all that has been done to them is to 
maintain them for some two days at the temperature which 
prevailed last August when you were using the miller’s flour? 

Baker: I say that it is impossible. 

Counsel: Then I am afraid you must prepare yourself for 


122 





BREAD-SHOP PRACTICE 


a shock, because that is just what the miller’s witnesses will 
directly prove. 

The obvious effect of such evidence was to show that the 
roi)e was not necessarily due to the miller’s flour, but to other 
causes which existed in the baker’s bakery at the time this 
millers’ flour was being used, since on the reproduction of 
those conditions rope was produced in January in the same 
baker’s bread from other miller’s flour. 

Another point of considerable interest arose during the 
case. First of all evidence was adduced which went to show 
that the miller’s flour was not in fact the cause of the rope. 
Then next it became necessary to deal with the alternative, 
that even if the flour were the primary cause of the trouble 
yet the miller could not be held to be responsible when he had 
supplied a particular type of flour ordered by the baker, and 
of which tendency to rope was one of the known qualities. 
Curiously enough, the law case submitted as governing this 
point was an American one, in which a boat had been ordered 
which it was stipulated should be built of a particular kind of 
wood. The boat decayed very rapidly and an action was 
brought for damages. It having been proved that rapid decay 
was an inherent vice of this special variety of timber, the 
court held that the buyer who had specified its use was respon¬ 
sible and not the boat-builder. The submission was made that 
liability to rope was similarly an inherent vice of standard 

flour, and the risk was that of the baker who had ordered it 
and not that of the miller. Eventually, the decision was given 
in favor of the miller. The underlying principles of this dis¬ 
pute were such as might arise in America as well as in Eng¬ 
land, and probably there also there would be a decision against 
the baker. 

A more general application is that although the baker in 
perfect good faith brought his action because with the change 
of flour he had escaped active rope, yet dormant rope had 
existed in his bread for months and manifested itself on the 
artificial production of conditions of summer temperature. 

The subject of rope has been dealt with very fully, because 
although rope trouble is happily comparatively rare, the effects 


123 





BREAD-SHOP PRACTICE 


are so serious that the baker should know sufficient of it to 
make its occurrence rarer still. 

Mouldiness and Mustiness. 

Certain other minor troubles which occasionally occur in 
bread are mouldiness and mustiness. If kept sufficiently long, 
it is practically the fate of all bread to go mouldy; green spots 
form on it and rapidly spread. These are generally due to the 
seeds or spores of mould falhng on the bread from the atmos¬ 
phere, where they rapidly develop. Mould in itself is a form 
of fungus, and stale or decajdng vegetable matter in the moist 
state is a very favorable medium for its growTh. Occasionally 
a fresh loaf becomes mouldy in as short time as a day^s age. 
In these rare instances the mould spores are probably in the 
flour, and having survived the act of baking rapidly develop 
in the bread. 

An occasional and more unpleasant complaint.is that of 
mustiness. Its essential feature is the development of an odor 
easily recognized but very difficult to describe. The smell is 
often observed in old damp straw, and is regarded as an effect 
of a particular form of mould or fungus known as mucor 
mucedo. This is usually caused by contamination of the flour, 
either during manufacture in the mill or while being manip¬ 
ulated in the dry state in the bakery. The spores or germs, 
having found their way into the flour, may remain quiescent 
until the moisture added at the doughing stage regenerates 
the fungus, which then speedily produces its characteristic 
and disagreeable odor and taste. A ready way to test flour 
for mustiness is to procure a clean flask or bottle. This and 
a clean cork should be washed until perfectly sweet in smell. 
Then put about an ounce of the flour in the bottle and half 
fill with water at about 140 degrees Falir. Cork and shake 
up several times during half an hour, then give a final shake 
at the end of that time and carefully smeU the contents. In 
this warm mixture any odor of mustiness or other smell taint 
is easily detected. If the flour is musty the matter should 
be threshed out with the miUer. If the flour is quite sweet 
on its arrival the trouble must have arisen in the bakery. The 
first step then taken should be to examine all bins and storage 
places for flour therein. In particular, if there are any ele- 


124 




BREAD-SHOP PRACTICE 

vators or conveyors through which flour passes to blending 
machines, etc., these should be taken to pieces and inspected. 
It is astonishing how a little flour may obtain a lodgment in 
some corner and remain there until seriously decayed and then 
get dislodged and worked up into the passing flour. The result 
will be a taint of the whole lot. The remedy is a thorough 
periodic cleaning of all such passages and odd resting places 
for small quantities of flour. 

Summary. 

(The causes of the production of sourness in bread have 
already been summarized.) 

The trouble known as ^'rope^' in bread is due to the action 
of a certain bacillus. 

It is criminal to attempt experiments on the production of 
rope in a bakery. Such experiments may be made in a bac¬ 
teriological laboratory or other suitable place outside with 
advantage. 

Test bakings are a useful form of experiment. The condi¬ 
tions under which these should be made are described. They 
serve to show that branny flours are the most liable to rope. 
Potatoes also may cause rope infection. Modern yeast is not 
likely to cause it. These point to the soil being the habitat of 
the rope bacillus. 

Acidity is inimical to rope development. 

How rope develops in an ordinary bakery. 

Watkins’s researches. Effect of temperature. Result of 
presence of acid. Flour practically always the source of infec¬ 
tion. Testing flour for rope in a rope-stricken bakery; baking 
method, test-tube method. 

Effect of extra moisture on ropy bread in presence of heat. 

Rope may enter a bakery through flour, but may after¬ 
wards permeate the whole building. 

Prevention of rope; the miller may take certain precau¬ 
tions. 

A student may start a regular system of rope tests in a 
bakery. 

Systematic cleansing and sterilizing of bakery utensils. 


125 





BREAD-SHOP PRACTICE 


.Procedure in case of complaint of rope in a loaf: At the 
consumer’s, in the bakery. 

Disposal of infected flour. 

Prevalence of^dormant rope. 

Responsibility of baker ordering a particular variety of 
flour. 

Mouldy and musty flour. Tests and remedies. 


126 




CHAPTER IX 

BAKESHOP MACHINERY 

The tour of the bakery has now been completed. Raw 
materials have been dealt with, and bread-making operations 
explained with special reference to fermentation and the 
causes by which it is affected. The finished loaf has received 
attention together with certain of the troubles to which it is 
liable. There yet remains the taking of a bird’s-eye view of 
the baker’s sources of power and mechanical appliances. To 
do this means another tour of the bakery, during which its 
machinery shall receive special attention. Also possibly some 
other new matters of interest may reveal themselves on the 
occasion of this second journey. 

Bakery Sources of Power. 

The primary necessity in the use of mechanical appliances 
in a bake shop is a source of power. The author remembers an 
illustration of one of the first dough-making machines that 
was offered to the baker. There was a hook handle at each 
end of the machine, and two bakers with ox-like patience were 
engaged in turning these handles and stirring the flour and 
water into dough. As a hygienic measure this machine may 
have had its advantages, but it never seemed brilliant as a 
labor-saving appliance, since, in addition to providing the force 
necessary to make the dough, the operative bakers had also to 
supply the motive power requisite to keep in motion the mass 
of metal which constituted the machine. Except in the case 
of the very largest factories the bakery differs from most 
other works in the fact that the power required is not con¬ 
tinuous but intermittent. Thus a flour mill has its machines 
going from the moment it starts work until work ceases, but in 
a bakery, while power is wanted for making dough and other 
similar objects, over long intervals it is not at all required. 
Where constant power is necessary, especially of a heavy 
character, the steam engine is commonly its best source; and 
where available, water power may also be employed. For the 
smaller bakeries, internal combustion engines, either gas or 


127 


BREAD-SHOP PRACTICE 


petrol, are very suitable and convenient sources of power. Of 
recent years electric motors affixed to each machine or group 
of machines have been somewhat largely adopted. Each type 
of power generator may be briefly considered. 

The Gas Engine. 

Not only are the baker’s power requirements inteimittent, 
but they are not usually sufficiently extensive to require the 
whole of a skilled engineer’s time to run and supervise an 
engine. So, too, they are wanted at only a minute or two’s 
notice, and this is another reason for ruling out the steam 
engine. The baker therefore asks for a source of power that 
can be readily started and as readily stopped, and one which 
ceases to consume fuel as soon as stopped. The man who has 
charge will usually not have had the training of an engine 
driver, and so the engine must be easily started and stopped 
by a man who is not a ajdlled engineer, and further it should 
run easily and well without a great deal of supeiwision and 
attention. The engine in fact requires to be of the type most 
expressly described as being “fool-proof.” Of such engines, 
the internal combustion type is one of the most convenient, and 
the kind known as the gas engine the most generally suitable 
variety of the type. The power in all these engines depends 
on the fact that appropriate mixtures of gas and air on being 
ignited explode or burn very rapidly, and so generate a large 
amount of energy which can be used as a driving force. The 
combustible gas may either be normally a gas, as coal gas, or 
a gas produced by the vaporization of oil, petrol or motor 
spirit; in any case the principle is the same. Speaking gen¬ 
erally, gas is the most convenient power for the baker, but in 
situations where it is not obtainable oil may be used and oil 
engines answer well for his purposes. Engines of the petrol 
type are generally run at high speed and would have to be 
geared down very considerably in order to run bakery 
machines. 

The “Four Cycle” System. 

The baker should understand the principle involved in 
explosion motors. It is in almost all cases that of the “Four 
Cycle” system. There is first of all the cylinder, to which is 


128 




BREAD-SHOP PRACTICE 


fitted a piston forming a gas-tight joint; valves control the 
admittance of the explosive mixture and the escape of the 
waste exploded gases. In starting the cycle, imagine the piston 
being at the closed end of the cylinder, i. e., furthest from the 
connecting rod and shaft. If the fly wheel be pulled round (by 
hand) the piston will be moved away from the cylinder end 
and will draw in a charge of explosive mixture after it. At 
the close of the outward stroke the inlet valve will be closed, 
thus leaving the closed cylinder full of explosive mixture. As 
the engine is pulled still further round, the piston returns to¬ 
wards the cylinder end and compresses the charge of gas; just 
as the engine advances a little further and the piston com¬ 
mences its second outward stroke, the contained charge of gas 
is fired by an electric spark or some other convenient means. 
An explosion ensues, and the piston is driven forcibly out¬ 
wards, giving an impulse to the engine in so doing. At the 
close of the outward stroke the exhaust valve opens and allows 
the spent gases to escape during the return or fourth stroke 
of the piston. There is then an empty cylinder ready to re¬ 
ceive a fresh charge of explosive gas, and so the work of the 
engine goes on. Summarizing the operations in the cylinder, 
the piston starting at the cylinder end, we have: 

No. 1. Outward stroke, cylinder fills by suction. 

No. 2. Return stroke, piston compresses the gas. 

No. 3. (Second) Outward stroke, gas is fired at com¬ 
mencement, explosion drives the piston out. 

No. 4. (Second) Return stroke, spent gases are forced 
out of cylinder. Cycle is completed, and No. 1 again 
commences. 

It is therefore only during one stroke in four that effective 
work is being done on the fly-wheel. This must be made 
sufficiently heavy to run smoothly, and without its speed of 
rotation being materially affected by the intermittent way in 
which it receives its propelling impulses from the cylinder. 
The arrangement of valves, contrivances for firing the gas, or 
other details vary in different makes of gas engine, but the 
underlying principles are throughout the same. 

The makers of gas engines issue a full card or book of 
instructions and these should be carefully followed. In erecting 


129 




BREAD-SHOP PRACTICE 


such an engine, it is well to have ample foundation, so as to 
absorb the shock of the series of explosions. The pipes for gas 
supply should be larger rather than smaller than recommended 
by the makers since town supplies of gas are not always main¬ 
tained at their full or proper pressure. Care of water pipes, 
lubrication, etc., should be carefully attended to according to 
directions given. When fitting an engine it should invariably 
have a driving pulley sufficiently wide to take the driving belt 
whether running on a fast or loose pulley. At the time of 
starting, the belt must be on the loose pulley so that the 
engine is running idle. The starting of these engines is done 
by pulling the fly-wheel round until an explosion takes place, 
when the engine runs of itself. The fly-wheel and moving 
parts must be well fenced in for puiT)oses of safety. At the 
same time this fencing must be done by a sliding gate or other 
similar contiivance which will peiinit ready access in order to 
start the engine. This once done, the sliding gate must at 
once be placed in its protecting position. Before stopping the 
engine, the main driving belt must be transferred to the loose 
pulley. 

Shafting. 

The power of the engine is in the first place directed to 
causing the main or crank shaft to revolve. The next problem 
is the transmission or distribution of the power from the 
engine to the various machines, and in the bakery this is con¬ 
fined to the conveyance of rotary motion from one shaft to 
another. There are two methods of doing this, one is by 
toothed wheels which gear one into another, a method con¬ 
tinually adopted in conveying motion from one part of a 
machine to another, and secondly by having a pulley on each 
shaft on the surface of which an endless line or belt may run. 
This latter is the usual method of conveying motion in the 
bakery. First of all a main or “line’" shaft is required and this 
is fixed where the various machines may be most conveniently 
driven from it. The engine and the line shaft are connected 
by the main driving belt, to which reference has already been 
made. 

The baker should understand something of the principles 
which govern dimensions, speed, and mode of fixing such 


130 



BREAD-SHOP PRACTICE 


shafting. First of all the engine must be absolutely level on 
its foundation, and so too the shaft must be quite horizontal 
or lined up perfectly true. The two shafts must be quite 
parallel, but one may be higher or lower than the other. The 
shafting itself is constructed of mild steel and is turned up true 
to its diameter throughout its whole length. Obviously the 
diameter will depend on the amount of force it has to transmit 
but a fair average diameter for small and medium bakeries is 
2^ inches. Such shafting is made in lengths of not more than 
20 feet which are joined together by ‘^couplings.^^ In order to 
carry the shaft proper supports are required; these may hang 
from the floor above, be wall brackets, or pedestals supported 
on a pier or girder. In any case they must be quite rigid. 
Whatever the design of the support, it carries a bearing for the 
running shaft. Such bearings may be of brass or white metal 
and are provided with efficient means of lubrication. Also, 
there should be means of adjustment, by which the bearing 
can be raised or lowered, and moved to and fro horizontally. 
There must be a sufficient number of these supports, and in 
particular, one or more should be provided at the points of 
greatest strain. Thus there should be one near the pulleys run 
by the main driving belt from the engine. The shaft is pre¬ 
vented sliding lengthwise by a pair of collars fixed on it, and 
running against the edge or end faces of one of the bearings. 

The diameter of a shaft is very closely associated with the 
speed at which it is run, as with the same amount of power to 
be transmitted, the higher the speed of revolution, the smaller 
is the diameter of the shaft required. With very small and 
rapidly revolving shafts all pulleys must be carefully balanced 
so as to prevent vibration, therefore too high a speed is not 
advisable. Bakery practice gives the speed for line shafts at 
from 140 to 160 revolutions a minute, and the diameter of shaft 
before specified will be sufficiently strong to convey the power 
necessary to drive ordinary bakery machines. 

Pulleys. 

These consist of wheels fixed on the shaft, the outer faces 
being turned true and either flat across, or slightly convex, 
i. e., higher or of greater diameter in the centre than at the 

131 


/ 





BREAD-SHOP PRACTICE 




outside edges. The machines to be driven are usually fitted 
with a pair of such pulleys, one being attached to the working 
parts of the machine and the other running loose by the side 
of it. These are called respectively the fast and loose pulleys. 
The maker of the machine will have indicated the number of 
revolutions the fast pulley is required to run at per minute. 
The driving pulley must be the width of the tw^o pulleys on 
the machine taken together. The older form of driving pulley 
was put in place by slipping it over one end of the driving shaft 
and then sliding it up to the place facing the pulleys of the 
machine. In order to secure this pulley to the shaft, a slot 
was provided in the boss or centre of the pulley, and a flat place 
to correspond was cut on the shaft. Into this slot a kind of 
wedge known as a key was driven, and this served to fix the 
pulley securely to the shaft. In more modem practice pulleys 
are now frequently made in halves which are put together 
enclosing the shaft and then securely bolted to each other. A 
pulley for a new machine is thus readily fixed without taking 
the shaft down or what was often necessary unkeying and 
removing pulleys already in position. In order that the pulley 
may giip the shaft, a friction material may be placed between 
the shaft and the inside of the hole in the centre of the pulley. 
The act of screwing the two halves of the pulley together, 
exerts sufficient pressure on the friction lining to hold the 
pulley securely to the shaft. The new machine must be erected 
so that its shaft is in a perfectly horizontal position and also 
so that the shaft is absolutely parallel with the driving shaft. 
This is usually determined or controlled by holding a straight¬ 
edge to the edges of the pulleys on the driving shaft and the 
machine. Touching the edges of each pulley in two places, the 
whole four points of contact should be absolutely in line. If a 
belt constructed of leather or suitable woven fabric is passed 
reasonably tightly over the tw'o pulleys it is evident that on the 
driving shaft and pulley being turned, the other or driven 
pulley will revolve also. 

First as to direction, if the belt is an open one, that is pass¬ 
ing from the top of one pulley to the top of the other, both 
shafts will revolve in the same direction. If possible this 
aiTangement should usually be chosen. At times it becomes 




I 


132 





7 


BREAD-SHOP PRACTICE 


necessary to reverse the direction of the driven pulley. In order 
to do this the belt is crossed in the middle and is known as a 
crossed belt. A moment’s reflection will show that as the upper 
edge of the one pulley is directly connected to the lower edge 
of the other, these two edges must be running in the same 
direction, that is the pulleys must be revolving in opposite 
directions. This may seem a little puzzling on paper only, but 
a study of running belts in the bakery makes it quite clear. 

In bakeries the driving shaft is conveniently fixed parallel 
to and as close as practicable to onq of the walls. The machines 
stand on the floor beneath it, and sufficiently far out to allow 
the requisite space behind them. Usually, therefore, the centre 
of the pulley or the machine is further from the wall than is 
that of the driving shaft, so that the belt descends obliquely, 
the one side being the upper and the other the lower side of 
the belt. A moment’s further consideration wiW show that it 
is always one side of the belt that is pulling the machine 
round; that is, the side on which the belt is travelling from the 
machine to the shaft. On the other side the belt is simply 
returning without doing any work. In other words one side 
of the belt is in tension, while the other is slack. The upper 
side should if possible be the slack one and so a driving shaft 
should as a rule revolve so that the top side of the pulley is 
moving toward the machine. The reason for this is interesting: 
If the two pulleys are of the same diameter, and the belt tight 
enough to lie quite straight from one to the other, exactly half 
the circumference of each pulley will be in contact with the 
belt. When a belt is being made to carry a load by driving a 
heavy machine, the side which is in tension will run nearly 
straight, while the slack side will drop in the middle or ‘"sag.” 
If the sag is on the top the belt embraces slightly more than 
half the circumference of the pulley, while if at the bottom it 
tails away from the pulleys and so is in contact with less of its 
surface. The more pulley surface that is in touch with the 
pulley, the less is the danger of the belt slipping.' Further, a 
belt drive should be as nearly horizontal as possible, and the 
belt should be run as slack as it will comfortably go without 
slipping. Unfortunately, bakery drives have often to be 


133 





BREAD-SHOP PRACTICE 


approaching the perpendicular, and are usually shorter than 
is most desirable in the interests of the belt. 

Size of Pulleys. 

The term size may be regarded as including the diameter, 
and the width of face of the pulley. Very important relations 
exist between the diameter of pulleys and their relative speed 
of running, and also the load on the belt. Taking the very 
simplest case: From a driving shaft it is necessary to convey 
driving power to a second driving shaft, or, as it is frequently 
called, a countershaft, which is required to run at the same 
speed. If a pair of equal diameter pulleys be placed on the 
shafts they will each make the same number of revolutions. 
This must be obvious, because their circumference, i. e., the 
parts in touch with the belt, must be running at the same rate, 
and as the circumferences are the same, each pulley must make 
a revolution in the same period of time. What is the difference 
then whether each pulley is one foot or two feet in diameter? 
First of all, the circumference of the larger pulley, and con¬ 
sequently the belt, will be traveling at twice the speed for the 
same number of revolutions. It may be taken as a general rule 
governing a traveling belt or rope that when conve 5 dng a con¬ 
stant load the strain or tension on it is in inverse ratio to the 
speed at which it is traveling. Therefore the strain on the belt 
of the larger pair of pulleys would be only half that in the case 
of the smaller. That the strain is less is clearly seen by looking 
at the matter in another way. Suppose in the case of the 
driven shaft the work to be done is equivalent to raising a 
weight say of 100 pounds at a constant speed. The line from 
the circumference to the center may be regarded as a lever, of 
which one of the spokes or arms of the pulleys may be looked 
on as the visible representation. In the smaller pulley the 
length of this lever is 6 inches, and 12 inches in the case of the 
larger. To overcome the same resistance, only half the pull 
has to be exerted on the longer lever as is required on the 
shorter one, but the end of the longer lever has to be pulled 
over twice as far. This is just what happens in the case of 
the larger diameter pulley. The belt is all the time exerting 
only half the pull, but it is traveling twice as quickly. In the 


134 






BREAD-SHOP PRACTICE 


same pair of pulleys, the strain on the belt is therefore as 
before stated inversely as their diameters. 

The next factor of size is the width, and the carrying 
power of a belt is directly proportioned to the width. Thus 
two belts one inch wide will convey twice the power of one, and 
similarly one belt two inches wide will carry twice the power 
of a one-inch belt under the same conditions. 

It follows that if you double the diameter of your pulleys 
you may halve the width of your belts. The practical reasons 
which determine the most favorable diameter and width cannot 
be discussed fully here, but the general principle may be laid 
down that pulleys should be as great in diameter as is prac¬ 
ticable and convenient. 

Having dealt with the problem of driving a countershaft 
at the same speed as the main shaft, and the bearing which 
the diameter of the pulley has on this subject, a variant arises 
in the case of the countershaft having to run at a different 
speed. As already intimated, 140 to 160 revolutions per min¬ 
ute is a convenient speed for the driving shaft. Suppose the 
number of revolutions to be 150, and it is required that the 
countershaft run at 200 revolutions, what must be the relative 
size of the two pulleys? If two pulleys of unequal size are 
coupled up, the speed of the circumference, or outside face of 
each must obviously be the same. If the driven pulley is only 
half the diameter and consequently half the circumference, it 
follows that it must make two revolutions to one of the other 
pulley. In the case of any two such pulleys, the smaller is 
always revolving the more quickly according to the rule that 
the number of revolutions is in inverse ratio to the respective 
diameters. To apply this to the case in question— 

As 200:150:: diameter of driving pulley : diameter of 
driven pulley. 

If the diameter of the driving pulley is 24 inches then— 

As 200:150: :24:18 inches, diameter of driven pulley. 

That is to say the driven pulley is in this case, three- 
quarters the diameter of the driving pulley. 

In the bakery outfit the speed of the driven pulley on the 
main shaft is another consideration. This has to be running 
at, say, 150 revolutions, and its diameter must depend on the 


135 






BREAD-SHOP PRACTICE 


number of revolutions of the engine shaft and the size of 
pulley supplied with same. If the engine shaft is running 
at 250 revolutions, and its pulley is 18 inches in diameter, then 

150:250: :18:30 inches 

which must be the diameter of the pulleys (fast and loose) on 
the main shaft. 

In the case of machines, the same, type of calculation 
applies. The makers will have indicated the speed at which it 
should run and the diameter of the pulleys must be obtained by 
measurement. Suppose these on the machine have a diameter 
of 12 inches and are required to run at 200 revolutions, then, as 

150:200::12:16, 

which must be the diameter of the pulley on the driving shaft. 

Belting. 

For bakery puii)oses, good leather belts are as suitable as 
any. The fitting of a new belt is one of the things that at 
times falls within the province of the baker. Spare belting 
should always be kept in stock, since a breakdovm may occur 
when least expected. For some little time new belting 
stretches considerably, and this has to be provided for by 
cutting the new belt a little short. Various contrivances are on 
the market for joining up the ends of belts, and among these 
those known as “Harris’" fasteners answer very well. They are 
made of malleable cast iron and consist of a series of teeth on 
a solid back, like bristles on a brush. One of these is taken, the 
length of which is a little less than the width of the belt. The 
two ends to be joined being placed together, the fastener has 
to be placed so that one pair of parallel rows of teeth are over 
each end of the belt. If the teeth are then driven into the 
leather the fastener holds the ends of the belt firmly together. 
The most convenient way to drive the fastener home is to lay 
the fastener teeth upwards on a firm block. The ends of the 
belt are then laid in position on it. An assistant should hold 
the belt firmly in the proper position, and then the leather 
should be hammered down on to the teeth of the fastener until 
it is quite home. After running for a few hours or a day or 
two, the belt will be found to have stretched considerably. It 
should be taken off, a piece cut out, and then refastened. 


136 




BREAD-SHOP PRACTICE 


Striking Gears. 

Mention has already been made of fast and loose pulleys 
and their use in starting and stopping the various machines. 
Suppose that there is a pair of 4-inch-wide pulleys on the 
machine, one fast and the other loose, then there will be fixed 
an 8-inch-wide fast pulley on the driving shaft. The belt will 
be 3 I /2 01* 4 inches wide. Obviously, if the belt is running on 
the loose pulley and the driving pulley, the machine will not 
be in motion. But if the belt is drawn over to the fast pulley 
the machine will start running, and will again stop when the 
belt is transferred to the loose pulley. To change the belt over, 
a fork is provided which operates the belt. This fork must be 
so placed that it is as near to one of the pulleys as possible 
and always so that the belt runs from the fork to the pulley. 
On gently pulling this fork over it shifts the belt from one 
pulley to another. The gear for actuating this fork must be 
easily accessible and provided with a pin or other means of 
locking it into both the ‘^on” and ‘W’' positions. 

Absorption of Power by Running Gear. 

To turn shafting and belting even though running idle 
absorbs considerable power, and allowance has to be made for 
this in deciding what margin of power has to be provided in 
the main motor. In a bakery with even 20 or 30 feet of shaft¬ 
ing some two or three horsepower is absorbed by the running 
gear. If this gear is allowed to get out of truth or unlubri¬ 
cated, the loss in this way may even be many times over the 
above figure. This leads us to our next point. 

Advantages of Electric Motors. 

These have the great advantage that one may be fixed to 
each machine or small group of machines. A most important 
result is that it eliminates the cost of, and loss on, running a 
lot of heavy shafting—often simply to turn an egg whisk or 
batter-beating machine at the end of the line. Further, the 
motor may be turned off as soon as it is finished with, and thus 
electricity is only being consumed while the work is being done. 
The relative economy of electric motors must depend on the 
cost of electricity at each place, but as a general rule, while 
actually running the cost is more than with gas or steam 


137 





BREAD-SHOP PRACTICE 


engine driven plants. This is more than compensated for by 
the absolute non-consumption while the machine is not 
running. 

The more advanced makers of machines are now offering 
machine and self-contained electric motor on one base. Natur¬ 
ally in this case the baker is saved all trouble as to determin¬ 
ing size and speed of motor, since the manufacturer has done 
all this for him. In other cases, where the machines are not 
provided with motors attached, the makers will furnish on 
application the amount of horespower required to drive the 
machine, and also size and power of motor (if asked for) that 
will do the work. In the case of grouping of machines, the 
engineer of the local electricity supply works will always be 
ready to advise as to size, etc., of motor required. It is 
always advisable to be on the safe side, and have a margin of 
power in the motor provided. 

Electric motors for works use have now attained a high 
degree of perfection. Speaking generally, they are exceedingly 
durable in construction and require from the baker little or 
no attention beyond keeping them clean, free from dust, and 
lubiicating when necessary. When motors do get out of order, 
it is well at once to call in the electric engineer, since repairs 
or adjustments are very technical and outside the scope of 
the baker. 


Underlying Principles of Electric Motors. 

The question of the principles and construction of the 
electric motor is too intricate to be discussed here, and there¬ 
fore the writer will simply indicate the fundamental laws 
which govern the construction of the motor. First of all, 
everyone knows that a magnet attracts a piece of iron. It 
follows that if a magnet is plunged in a pile of iron filings, 
they are attracted and adhere in bunches to the magnet. A 
fact which is not so well known is, that a wire conveying an 
electric current behaves just as a magnet. Let the student 
take a piece of copper wire which has no natural magnetism 
whatever, and pass an electric current through it, either from 
a battery or an electric supply. Such use of an electric supply 
should only be made in event of sanction by the technical 


138 



N 


_ BREAD-SHOP PRACTICE _ 

authorities controlling the supply. On dipping the wire con¬ 
veying the current into iron filings they at once stick to it as 
though it were a magnet. On interrupting the current, the 
magnetic properties of the wire cease and the filings drop off. 
This may be repeated as often as desired. From this very 
elementary experiment to the modern electric motor is a far 
cry, but still perhaps we may succeed in bridging the gap. Sup¬ 
pose, in the machine we call an electric motor, there is a wire 
which we can electrify and de-electrify by the agency of the 
machine itself. Next, that within the magnetic field of such 
electrified wire there is a piece of iron, and that this piece of 
iron is so arranged that if it and the electrified wire act on 
each other they cause a shaft to which one or other is attached 
to go through part of a revolution. Such attraction will result 
in the shaft of the motor moving; then, if when the piece of 
soft iron is opposite the electrified wire, the current is cut off, 
the moving part will proceed by its own impetus. If another 
such piece of soft iron comes within the magnetic field of the 
electrified copper wire, another such pull is given and the shaft 
is pulled a little further round and liberated by the wire ceas¬ 
ing to be electrified. It is only a matter of mechanical con¬ 
trivance to provide that this series of electro-magnetic im¬ 
pulses should follow one another sufficiently regularly and 
rapidly to impart a continuous rotary motion to the shaft of 
the motor. This is the underlying principle of electric motors. 
Its elaboration and adaptation cannot be dealt with in a book 
of this description. 

General Bakery Machinery. 

In the endeavor to cast a glance at these, only the First 
Principles can receive attention in this work. In many cases 
where the object aimed at is the same there are different ways 
of attaining the result, so that we must confine ourselves to 
the Principles, to the exclusion of the details. 

To take machinery in regular order, probably one cannot 
do better than follow the flour, from its arrival at the bakery, 
through all its changes to the finished loaf which is dispatched 
to the consumer. 


139 





BREAD-SHOP PRACTICE 


Sadt or Barrel Hoist. 

On arrival of flour at the bakery, some means have to be 
provided for its being transferred to the flour store. This is 
generally at the top of the building, and I wonder whether 
many bakery students have bothered to think why it is there. 
The answer is that during the various steps of bread-ma!dng it 
is desirable that flour and bread should follow the operation of 
gravitation, and fall rather than have to be raised during the 
process of manufacture. The hoist is a machine which, by 
means of a chain, draws the flour from the car or wagon to 
the floor on which it is required. If there are several floors it 
is well to have a pair of trap doors on each which rise as the 
barrel is hauled upwards and then drop, thus always securing 
a safe floorage. The hoist itself is a very simple machine and 
must be passed over without further description. 

Flour Blending. 

There are comparatively few bakeries in which one variety 
of flour alone is used. Where there is more than one, some 
method of mixing must be adopted. In older hand-working 
bakeries the different flours were discharged into the trough 
and turned over by hand until a fairly good mixture had been 
obtained. In flour mills, the commoner method of mixing is to 
take various streams of flour, cause them to converge into 
one channel and there trust to the action of the revolving 
worm, in the conveyor itself, to mix the flours. Occasionally 
a ready-made flour of a different variety is mixed in with the 
ordinary product of the mill. For this purpose the ready-made 
flour may be placed in a bin from which, by means of a shoe- 
feed or other mechanical contrivance, it is fed in constant and 
regulated quantity into the stream of flour being manufac¬ 
tured. Mixing is effected by the worms or other devices by 
which the flour is moved forward. The bakerv differs from 
the mill in this respect, in that all the flour to be used is already 
separated off into weighed quantities. In America these will 
consist of the barrel of 196 pounds or a definite fraction of 
same. If the baker has decided on a mixture of two parts 
of Flour A to three parts of Flour B, or whatever other pro¬ 
portion he may desire, the simplest plan is to take two barrels 


140 





BREAD-SHOP PRACTICE 




of the one and three barrels of the other; an efficient mixing 
machine then consists of a sufficiently large trough to which 
is fitted a mixing blade, bj^ which the flours are thoroughly 
incorporated. After this the flour may be drawn off and 
weighed in convenient quantities. 

Sifting Machines. 

Before going to the dough-making machine it is well that 
all flour should be carefully sifted. For this there are two 
reasons. First of all, it is essential that all extraneous matter 
should be removed from the flour before it is made into dough. 
With flour that has been packed in bags or sacks, it is astonish¬ 
ing the quantity of fluff from the bag material and twine, that 
IS thus removed, to say nothing of an occasional sack needle. 
In the case of barrels, there is the possibility of nails, wood 
splinters, etc., to be got rid of. The second reason is, that any 
lumps of wetted flour are then separated, while masses of damp 
or caked flour are broken down by the action of the machine, 
f’urther, all the flour is lightened and rendered more lively. In 
other words, it is thoroughly aerated by its passage through 
the sieve of the machine. It has already been explained how 
the oxygen of the air acts as a stimulant to yeast, and a flour 
thus treated is rendered more amenable to fermentation when 
made into dough. The machine itself consists of a sifting 
arrangement through which the flour is caused to pass by 
means of a brush or other analogous contrivance. On emerging 
from the machine the flour is in a very light condition, accord¬ 
ingly it is well to provide a sleeve by which it is conveyed direct 
to the doughing machine. 

Water Measuring and Attemperating Tank. 

In modern bread-making appliances, accuracy of weighing 
and measurement is essential. Not only, as before explained, 
must the flour be weighed, but the exact quantity of water 
at the right temperature must also be measured. For this 
purpose a tank is provided, which is fitted with a hot and cold 
water supply. The former is best connected to the bottom of 
• the tank and the latter to the top. The tank is also provided 
with a good thermometer, and a glass gauge fitted with a 


141 





BREAD-SHOP PRACTICE 


scale of quarts or other unit of measurement. This scale 
should read from the top downwards. The measured quan¬ 
tity of water is allowed to pass through a stopcock into the 
trough of the doughing machine. The quantity and tempera¬ 
ture of the water being known, an approximate amount of cold 



Me^surln^ 

Tdnky 


water is run in. Hot water is then carefully added until the 
desired temperature is obtained. The hot water, being lighter 
than the cold, rises from the bottom when introduced and 
rapidly permeates the whole mass. The operator should wait 
until the temperature of the mixture becomes stationary and 
then note the position on the gauge. If at, say, 5, and 60 
quarts are required for the dough, the water is allowed to run 
in until the 65 mark is reached. A portion of the water is 
usually drawn off into a pail in order to break down the yeast. 


142 


















































































_ BREAD-S H OP PRACTICE _ 

Some of these tanks are fitted with a sliding* scale, in which 
case the zero of the scale is adjusted to the surface of the 
water and then the exact quantity run in by the scale, by 
which any calculation is obviated. The accompanying figure 
is an illustration of such a tank. 

For use in summer it is well to provide the tank with a 
perforated tray at the top, in which ice may be placed in order 
to cool the water when such a step is necessary. 

Kneading Machine. 

Reference has already been made to this appliance, and to 
the general operation of dough-making. By means of moving 
arms or blades, flour and water (with other ingi’edients) are 
mixed into dough, which is then discharged into a trough and 
allowed to ferment. It is a good plan to provide for this pur¬ 
pose a special room kept at an even temperature. 

Dough Weighing Machine. 

The only machine to which this title really applies is the 
common or garden set of scales and weights, by which bakers 
weigh the dough as they cut it up into loaf weight pieces. 
This mode of scaling was aptly described to the author by a 
foreman baker as ^‘half a weigh and half a guess,” and un- 
doubtly led to many irregularities in the weight of bread. In 
the more modern machine bakery the problem of successful 
mechanical ‘‘weighing” of dough has been solved by methods 
which are not really weighing, but actually the measuring of 
pieces of dough. An efficient type of machine consists of a 
device by which the dough is caused to fill a series of cylinders 
and is then cut off from the supply. The volume of these 
cylinders is arranged so that a piece is cut off which has just 
such a cubic capacity as represents the desired weight of 
dough. The dough is thus cut off into pieces of a definite 
volume, and these go on to the subsequent processes of bread¬ 
making. In practice such machines are provided with an ar¬ 
rangement for adjusting the volume. Usually, on starting the 
machine a few pieces of dough are weighed on a pair of scales 
as they emerge from the machine and the adjustment is altered 
one way or the other until they are of the desired weight. It 


143 








BREAD-SHOP PRACTICE 


is obvious that the degree of accuracy of these machines must 
depend on the cylinders being always exactly filled, and with 
the dough in the same state of compression. On the other 
hand, the dough must not be handled roughly enough to injure 
its rising power. Among various types of these machines are 
some in which the dough- is forced forward by a screwing 
action somewhat after the fashion of a sausage machine. 
These, however, very materially impair the resiliency of the 
dough. Probably the best device is one of simple compression. 

Moulding and Its Nature. 

Having been weighed off the dough is next moulded, that 
is, it is shaped up into pieces that will bake into loaves of the 
desired form. Moulding is, however, much more than giving 
a piece of dough any desired external shape. This is best 
demonstrated by watching an expert baker moulding loaves. 
A piece of dough is taken in each hand, and rolled on the table 
in a peculiar way. The outer skin of the dough is drawn down 
to the lower part of the loaf, which is just under the “heel” 
of the hand. Here it gets tucked or worked in to the mass of 
the dough. This goes on until the moulding has sufficiently 
progressed. An examination of the loaf shows that it has 
acquired a distinct internal structure. There is a concentric 
arrangement of the dough which has been compared to the 
foiTuation of an onion. This structure is well shown by the 
disposition of the gas bubbles within the loaf. After being 
baked, the same internal formation is noticeable in the bread. 

Moulding Machines. 

The task set the inventor of such a machine is a difficult 
one. Not only must the loaf be rounded up, but it must also 
have this peculiar treatment, above described, given to it. 

The following anecdote of a moulding machine may be of 
interest and service. The author was one of a small party 
invited to a well-known British bakery to inspect in the very 
early days a new moulding machine at work. The proprietor 
of the bakery and the inventor were acting as demonstrators. 
The machine itself was very interesting. A series of shallow 
saucers were carried on uprights on an endless belt. At the 
one end the pieces of dough were being fed on to the saucers; 


144 



BREAD-SHOP PRACTICE 


as they moved forward they were clasped between a pair of 
metal hands, and again released. A second pair of hands gave 
a squeeze in another direction. This process continued until 
the loaf emerged as a well-shaped round ball. In watching the 
machine one was impressed by the resemblance of the action 
to that of a schoolboy squeezing snow into a snowball. The 
machine was working away steadily, while near by a number 
of bakers were moulding dough by hand. The writer signaled 
to one of these and asked him to bring one of his loaves and 
a dough knife. With this he requested the baker to cut through 
one of the machine-moulded loaves and also one of his own. 
The hand-moulded loaf showed all the desiderated concentric 
structure. That, however, of the machine-treated dough was 
destitute of any definite internal arrangement whatever. Fur¬ 
ther on, comparing the two, the machine-moulded loaf gave the 
impression of being loose and likely to ‘Tall in pieces’" in baking 
compared with the other. No remark whatever was made on 
this demonstration, except that the inventor asked the bakery 
proprietor the name of the gentleman who had asked for the 
loaves to be cut. 

Some months elapsed, and again the author was invited to 
see a new moulding machine at work. Somewhat to his sur¬ 
prise the inventor was the same, but the machine was very 
different. A rolling action had been adopted; and one could 
see that the loaf was not merely being shaped, but that an 
effect analogous to that of hand-moulding was being produced. 
The inventor cut a loaf from the machine, and showed its 
interior texture. This was one of the very first moulding ma¬ 
chines that really moulded. In the course of a very interesting 
conversation, the writer asked what had become of the earlier 
machine, and got the reply from the inventor that he had 
mentally scrapped it on seeing the writer cut and compare the 
two loaves. As the essential part of the story was told by 
the inventor himself, the writer feels at liberty to relate it 
here. And the moral is, that moulding machines must give 
the true moulded texture to a loaf, else they are of very little 
service. 

Moulding machines are of diversified form, but the success¬ 
ful ones of the present day exert a definite moulding action on 


145 




BREAD-SHOP PRACTICE 


the loaf. It may be asked, how does machine moulding com¬ 
pare with hand moulding? The probably -correct answer is 
that the very best hand moulder will do better work than the 
machine. One reason is that he exercises judgment. If he 
gets hold of a piece of dough which is unduly slack or ragged 
in texture he will give it a little more work than usual and so 
turn it out a good loaf. The machine has not this power, and 
if an imperfect loaf emerges from it it goes on its way un¬ 
touched. But as a set off, the machine moulds much better 
than the bad moulder, and it may be fairly claimed that a good 
moulding machine does better average work than an ordinary 
set of table hands. 

“Proof” of Dough. 

In England moulding is almost always done in two instal¬ 
ments, the first of which is generally called “handing up.” The 
hand moulder drops his loaves as handed up into a drawer, 
which is closed when full. There it remains for a time, until 
fermentation has restored the gas pressed out by handing up 
and the loaf is once more lively and elastic to the touch. When 
in this condition the loaf is said to have got or acquired 
“proof.” The writer has not been able to trace the origin and 
derivation of this teiTn as applied to the loaf. Certainly it is 
not used in the ordinary dictionary sense which defines proof 
as “that which convinces the mind.” A secondary definition 
is that proof is a measure of the degree “of strength in spirit,” 
and a strong spirit is spoken of as being of “full proof.” It 
may possibly be that a loaf in full proof is one which is of full 
volume, strength and resiliency. In order to give a loaf proof 
a frequent device is to place it in a warm cupboard, by which 
fermentation is stimulated. As the operation referred to 
under this name is not the process of convincing the mind, it 
has been proposed to call the process of thus treating a loaf 
“proofing” rather than “proving.” One would then speak of 
a proofing cupboard. But although this distinction would have 
its advantages, it has not been generally adopted, and the 
baker usually speaks of “proving” his loaves. After “proof¬ 
ing” in a drawer or cupboard the hand baker proceeds to work 
his loaves into shape once more, and this second operation goes 
by the name of moulding. 


146 




BREAD-SHOP PRACTICE 


In installations of machinery, this period of proofing after 
passing through the handing-up machine must be provided for. 
Accordingly the handed up loaves are conveyed to a proofing 
cupboard through which they pass slowly. The object is to 
provide the requisite time in a warm atmosphere for proofing 
to go on. This may be anything from 15 to 25 minutes, and 
at the end of that period the loaves are discharged from the 
proofer on to the second or moulding machine. Here they re¬ 
ceive their final shape and also true moulded texture. A very 
large proportion of English bread is baked into cottage loaves 
of 2 pounds each. The cottage is two storeys high, and accord¬ 
ingly the loaf is divided into two pieces, which are moulded 
separately and placed one on the top of the other. The upper 
piece vsdll be roughly one-third the weight of the lower, but 
the exact proportion varies according to the fancy of the 
maker or the requirements of the district. The cottage mould¬ 
ing machine is fitted with a contrivance which cuts the loaf 
into the two pieces and moulds them separately. Again the 
proofing has to be gone through, the two parts of the cottage 
loaf are “bashed’’ together, and baked into the two-storeyed 
loaf. 

Summary. 

Bakery sources of power, 

The gas engine, principles of. 

The four cycle system. 

Shafting, dimensions, speed, mode of fixing. 

Pulleys, whole and split. 

Belt drives. 

Size of pulleys, relation to carrying power, and width of 
face. 

Calculations arising out of the relation between size and 
speed of pulleys and shafting. 

Belting and belt-fasteners. 

Striking gears. 

Absorption of power by running gear. 

Electric motors, advantages of. Underlying principle of 
such motors. 

General baking machinery, bird’s-eye view of. 

Flour hoisting. 


147 




BREAD-SHOP PRACTICE 


Flour blending: Different position of miller and baker in 
this matter. 

Sifting machines. 

Water measuring appliances. 

Doughing machine. 

Dough weighing machines. 

Moulding and its nature. 

Moulding machines; defects of earlier types and improve¬ 
ments on. 

‘‘Proof” of dough and provision in moulding machinery for 
its occurrence. 


148 




CHAPTER X 


BAKING AND ASSOCIATED HEAT 

PROBLEMS 


Operation of Baking—Primitive Oven Types. 

It is the actual act of cooking the loaf, when ready, by the 
process of baking, which has given the manufacturer of bread 
his trade name of baker. Early baking methods were primi¬ 
tive in their character, but the results were often delightful. 
The English farmer of, say, fifty years ago baked bread in a 
very simple but nevertheless effective way. No doubt the 
American farmer had also analogous efficient methods. The 
baking trade of the present day pays one of the highest com¬ 
pliments to its predecessors by naming some of its best 
flavored products '‘home-made” or "farmhouse” bread. The 
writer’s personal recollection is that a brisk fire was made on 
the hearth, of dried hazel or other sweet-smelling twigs. This 
having burned down, a clean place was swept in the middle 
of the hearth, the piece of dough was placed there, and cov¬ 
ered with a shallow iron pot. The embers were drawn over 
it, and the fire allowed gradually to bum itself out. At the 
close the ashes were removed and a well baked loaf was the 
result. 

The baker’s oven had to provide for the baking of a much 
greater quantity of bread. One of its earliest forms seems to 
have been a box or receptacle, cupboard if you like, constructed 
of brickwork. A door was provided in front, and the interior 
space might be, say, six feet square and eighteen inches to 
two feet high. The floor or oven sole would be level, while 
the roof or crown was usually arched. To fire this oven, small 
wood was burnt inside it. This made the oven hot, the ashes 
were withdrawn, and the bread to be baked inserted. The 
door was closed, and baking allowed to proceed. It will be 
noticed that the baking was done by the heat stored up in the 
structure of the oven itself. The operation of baking was 
therefore intermittent; first the oven was heated, then the 






149 


BREAD-SHOP PRACTICE 


bread was baked and the oven gradually got cooler. When 
necessary it was reheated, after which baking could again 
proceed. 

Side-Flue Oven. 

An important advance was made when the side-flue oven 
was invented. Ovens had gradually grown in dimensions 
until an internal space of 12 feet from door to back and 12 
feet in width was no uncommon measurement. The sole of 
such an oven would be constructed of tiles of Are clay, which 
in Scotland were frequently replaced by stone slabs of a spe¬ 
cial variety. The roof was, as before, arched. The oven door 
was usually in the center of the front. On the one side was 
built in a furnace, consisting of fireplace and ash pit. The flue 
from this led direct into the oven. A flue leading to the 
chimney was situated on the other side of the oven door. A 
coal fire was usually employed in these ovens, and on opening 
the dampers the current of air and flame went direct to the 
back of the oven on the one side, was reflected, and came for¬ 
ward again to the flue on the other. For an oven of this type 
which was properly designed the heat current traversed the 
whole oven interior. The sole of the oven would have about 
^ three feet of oven material beneath it, the side and back walls 
would be composed of some two feet thickness of brickwork, 
above the oven chamber there would be three or four feet of 
brickwork and a layer of sand. An oven would therefore con¬ 
sist of a baking chamber inclosed in a good many tons of non¬ 
conducting material. A new oven would take a considerable 
time to get hot through, but when this was accomplished 
comparatively little heating was required for each day's 
baking. At a time found most convenient, each day, a fire 
would be made and allowed to burn itself out. The oven would 
be closed and the heat would be absorbed and stored within 
the brick work. Possibly, before baking, a brisk fire would be 
drawn into the oven. This gave a charge of very hot air and 
also a surface absorption of comparatively intense heat. This 
was called by the baker a “flash heat." 

The bread is loaded into such an oven by the well-known 
“peel," which is a species of spade or shovel. Naturally the 
oven is hotter at the front than at the back, as a result of the 


150 




BREAD-SHOP PRACTICE 


situation of the fire. This is, however, compensated by the 
fact that the bread at the back must be put in first and taken 
out last. The flash heat gives the first baldng effect, and from 
its rapid action causes the bread to rapidly increase in volume 
—“draws up” the bread, as the baker calls it. But after the 
first effect it is the deeper stores of heat in the material of the 
oven which carry on the baking; this is what the baker calls 
the “solid heat.” The small baker would, with his hot oven, 
bake first the goods which require a high temperature, and 
then those baked at a less degree of heat, and finally rich cakes 
and other goods which are baked at a comparatively low tem¬ 
perature. 

A good oven of this kind was highly esteemed by bakers, 
many of whom, if possible, would not use any other type; and 
further, many could not if they would. Bread baked in such 
an oven was held to be exceptionally sweet in flavor, while the 
crust was fairly thick and short in texture. The inequalities 
of heat gave the baker sufficient variety from high-baked to 
low-baked loaves to meet the different wants of his customers. 
But in spite of all care, there was generally a percentage of 
burnt loaves which were difficultly saleable, while in any case 
they were of very short weight. Notwithstanding all its faults, 
for the old-fashioned family small trade this oven in competent 
hands did remarkably well, and if more or less superseded in 
modern times it goes into honorable retirement with a good 
record. 

Probably the defects of the side-flue oven which most 
attracted attention were the intermittent capacity of baking 
which it possessed coupled with the irregularity of the prod¬ 
uct. Then much of the bread was unduly dried off in the bak¬ 
ing, and short weight loaves were the result. This contains a 
foundation of truth, but if a certain quantity of flour food- 
solids are placed in the oven, the baking which yields the most 
pleasant flavored (tasty) loaf will make a comparatively short 
weight loaf. The driving off of that last ounce of water will 
wonderfully improve the bread, without sacrificing one iota of 
its solid food constituents, but by legislation the public forbids 
this and will insist on getting its pound of flesh in the way of 
full weight. Very well, the baker has no objection to supply it, 


151 



BREAD-SHOP PRACTICE 


but the public buys that last ounce of water at the price of all 
the bread improvement which results from its elimination. 
This is by the way. Then another defect was the great amount 
of fuel consumed per sack of flour baked. 

All these difficulties stimulated the minds of inventors. ''Fhe 
line on which they concentrated was continuity of baking. This 
led to the evolution of two types of oven, each of which merits 
description. 

External Flue Oven—Principle of Continuity. 

• 

Very efficient and well thought-out ovens have been built of 
this kind. Briefly, there is first a furnace, from which the 
heated gases are led in flues underneath the oven sole, after 
which they are conveyed to flues over the crown of the oven. 
For this type of oven, the crown is horizontal, and is con¬ 
structed of thin tiles, say ly^ inches thick. Both bottom and 
top heat are thus supplied. The proper apportionment of the 
two is provided by the thickness of the intervening layers of 
material between the flues and the bottom and top of the oven. 
In addition dampers were provided by which the heat of the 
furnace could be diverted direct to the top when necessary. 
Ovens of this kind met with considerable success—^there was 
an equable distribution of heat and top and bottom of loaf 
were evenly baked. The use of brick and tile construction 
tended to give solidity of heat as compared with the variations 
introduced by the employment of metal. Bread was thus 
baked in as nearly as possible an air-tight chamber. Loss 
of weight during baking was reduced to a minimum, but the 
resultant loaf had necessarily a thin and somewhat tough 
crust. An additional advantage was that there were no loaves 
lost by burning. The ovens were economical in fuel, and were 
externally heated; further, the furnace and stoke hole could 
be placed anywhere, and preferably outside the actual bakery. 

An essential feature of this oven in the minds of the in¬ 
ventors of various types was the principle of continuity. The 
introduction of a batch of bread in the oven in no way inter¬ 
fered with the firing, since the flues were absolutely external. 
Therefore the idea, was to keep a slow and continuous fire the 
whole of the time, thus maintaining the heat of the oven. The 
baker, however, elected to treat this oven just the same as he 


152 



BREAD-SHOP PRACTICE 


did his old side-flue, and to heat up to baking heat, and then 
to close down his fires while baking was in progress, and thus 
to continue these operations alternately. A good deal of the 
early difficulties with these ovens, known sometimes as hot air 
ovens, was due to this mode of treatment. 

Steam Pipe Ovens. 

These introduced a completely new departure. Every 
student of the Laws of Heat is aware that the boiling point 
of any liquid is dependent on the pressure to which it is sub¬ 
jected. In a vacuum, water boils at a much lower temperature 
than in the open. Further, on high mountains where the 
atmospheric pressure is considerably less than at the sea level, 
water boils at such a low temperature that such ordinary 
cooking operations as the making of tea and the boiling of eggs 
become practically impossible. These observations when re¬ 
duced to actual figures show that water may be made to boil 
in an approximate vacuum at a temperature of 70 degrees 
Fahr. (21 degrees C.), and that at an altitude of 15,940 feet 
the boiling point is 185 degrees Fahr., with the barometer 
standing at 17.5 inches. When the pressure is increased beyond 
that of the atmosphere, the effect is just the opposite. Thus 
if water is heated in a confined space, such as a high pressure 
boiler, as the pressure of the steam increases, so also does the 
temperature. At 150 pounds pressure to the square inch, the 
temperature of both steam and water is 356.6 degrees Fahr. 
(180.3 degrees C.). At 300 pounds to the square inch the 
temperature becomes 415.4° Fahr. With higher pressures, still 
higher temperatures are obtainable. For this purpose water 
may be inclosed in pipes made either of iron or mild steel, 
having a bore of about 1/2 ii^ch and the same thickness of wall. 
Water may be heated in such pipes to a temperature suffi¬ 
ciently high to evolve heat at the baking point, and this is the 
underlying principle of steam pipe ovens. 

As a means of oven heating, Perldns, of London, was the 
inventor of the steam-pipe process. In the very earliest ovens 
of this type a complete circulating arrangement, based no 
doubt on house heating installations, was the plan devised. The 
circulating pipe traveled under the sole of the oven and also 
just beneath the crown, a coil of the pipe being fixed in an 


153 





BREAD-SHOP PRACTICE 


independent outside furnace. Here heat was applied to the 
pipe and circulation of water and steam at a high temperature 
resulted. In this way the interior of the oven was raised to 
baking heat. 

At a later date the circulating pipe w^as replaced by a 
series of single pipes, each pipe being of such length as to 
extend to the front of the oven and have a piece some six to 
twelve inches long projecting into the furnace. These pipes 
were about to % inch internal diameter, and with walls of 
% to 1/2 inch in thickness. They w^ere constructed of wrought 
iron or mild steel. One end of the pipe was welded solid, and 
then a charge of pure water inserted. The other end was then 
also welded up, and thus each pipe got a permanent charge of 
water. When laid in place in the oven the pipes had a slight 
rake or dip toward the furnace, which caused the water to lie 
at that end. On being heated the water boiled and thus filled 
the whole of the pipe with steam. As the heat of the furnace 
increased, the pressure of steam and the boiling point of the 
water also increased, until at length they were sufficient to 
heat the pipe to a temperature sufficient f6r baking. During 
this operation of heating up a cold pipe, the steam first pro¬ 
duced would be condensed in the upper part of the pipe in the 
oven and return as water to the furnace end. This continuous 
cycle would go on until the pipe was hot enough; at that stage 
the introduction of cold dough would abstract heat from the 
oven and series of pipes, and that heat would be replenished 
by further condensation of steam, and its reproduction in the 
lower part of the tube. In earlier ovens there was a furnace 
at the back of the oven, practically the whole width so as to 
take all the tube ends. Now, such tubes are bent and shaped 
so as to bring all the ends into a comparatively small and 
compact furnace. The result is a considerable saving in fuel. 
It has been well said of this oven that it is externally fired and 
internally heated. Like the extemal flue hot air oven, the 
steam pipe oven is in principle a continuous oven, and the con¬ 
struction practically compels the user to adopt a continuous 
rather than an intermittent method of heating and using. 

Heat Problems. 

The present is an appropriate place in which to deal with 
certain matters in relation to heat which have not as yet re- 


154 




BREAD-SHOP PRACTICE 


ceived attention, but which are of great importance to the 
baker. 

The whole of the heat which we use for any purpose what¬ 
ever is derived from the sun, the only possible exception being 
that obtained from tidal sources, since this latter may be 
looked on as derived from what is really a sort of brake on the 
revolutionary motion of the earth and a conversion of such 
motion into heat. One cannot, however, utilize the sun's heat 
for baking purposes in any direct fashion. One hears of 
places where an egg may be cooked by exposing it in the 
broken condition to the direct rays of the sun, but even in such 
districts the direct sun's heat can not be used for baking bread, 
in an oven or any other manner. What one has to fall back 
on is, therefore, the combustion of various kinds of fuel, and 
the whole of these have been built up by the action of the 
sun's warmth. Animal fuel is not often employed, though fat 
could, in fact, be used. Most fuel is therefore of vegetable 
origin. The simplest instance is where straw or even grain is 
burnt for the sake of the heat it produces. In such cases the 
previous summer's' sun is being utilized. Under its influence 
the plant grew and built up its tissues of substances composed 
largely of carbon and hydrogen, and thus we gain our warmth 
from the sun of yesteryear. 

With wood, the process of growth under the sun's rays has 
lasted a longer time, but still what has occurred is that, in 
virtue of the sun's warmth, gaseous inert carbon dioxide has 
been so acted on chemically that the carbon in a comparatively 
unoxidized condition has been built up in the substance of the 
tree and the oxygen discharged into the atmosphere. 

In the case of coal we have a fuel produced during aeons 
rather than years. In some of the earliest geological ages, 
when the earth must have been much hotter, there was a 
period of luxurious vegetation. The resultant growths were 
submerged, covered by clay and sand which changed into rock, 
and thus protected. The result is coal, which, however, has 
materially changed from the wood from which produced. 

As a result of chemical changes, liquids have been evolved 
which constitute our various petroleum deposits. Further, 
some portions of the original deposits have been expelled in 
the gaseous form, and these when tapped are reservoirs of 


155 




BREAD-SHOP PRACTICE 


natural gas. But all these are ultimately stores of sun’s heat 
accumulated ages ago, and preserved within the earth. They 
are now our principal sources of heat for practically all pur¬ 
poses. Coal may be used as fuel direct, or under the influence 
of heat may be split up into gas and liquid products, leaving 
a carbonaceous residue, known as coke. The gas, the coke, and 
also some of the liquid products, may be used as fuel. 

The utilization of fuel entirely depends on the fact that 
certain substances, which are conveniently classed as inflam¬ 
mable, combine fairly readily with oxygen, and so evolve con¬ 
siderable heat. Among these bodies are the elements carbon 
and hydrogen. Their compounds, known as hydrocarbons, 
belong to the same category. Then there is a group of bodies 
also containing oxygen, of which starch and the other carbo¬ 
hydrates may be cited as examples. In so far as they contain 
combined oxygen their value as fuels is to that extent dim¬ 
inished. (In passing it may be mentioned that combination 
with chlorine, e. g. of hydrogen or phosphorus, is also a source 
of heat, though of no practical significance.) Careful deteiTni- 
nations have been made of the heat evolved by the combustion 
of some of the more important sources of fuel. The student 
will remember our measure of heat, that is, the heat unit or 
quantity of heat which will raise 1 gram of water from 
0 degree to 1 degree Centigrade; and that this is usually 
employed in heat measurements. The following table gives the 
results of such determinations of the heat evolved by the com¬ 
bustion of 1 gram of each substance: 


Heat Developed During Combustion 

Heat units. 


Hydrogen, Ho . 

Carbon, C. 

Carbon monoxide, CO. 

Marsh gas, CH 4 . 

Alcohol, C 0 H 5 HO . 

Coal from about. 7,780 to 

Coke about. 

Wood (dried in air) . 


34,462 

8,080 

2;634 

13,063 

6,909 

8,240 

7,000 

3,547 


156 












BREAD-SHOP PRACTICE 


It will be noticed that, weight for weight, hydrogen has the 
greatest heating capacity of all substances, being over four 
times that of an equal weight of carbon. Marsh gas, or methyl 
hydride, has a high heat combustion. Alcohol, although a 
valuable fuel, has its heat of combustion materially cut down 
by the oxygen it contains. Various coals have a heat depend¬ 
ing on their composition, and run close to that of carbon. It 
must be remembered that these bodies contain not only carbon 
but also hydrogen, and in addition more or less oxygen. 
Further, there may be more or less water extraneous to the 
actual molecule; this is, not merely non-heat-producing, but 
also a waster of heat by actual absorption. Wood has a much 
less heat value than coal. Coke from a pure coal should be 
pure carbon; however, it includes in fact the ash as well as the 
non-volatile carbon of the coal. Further, coke also frequently 
contains extraneous moisture and so has its fuel value dim¬ 
inished. Altogether, coke has about seven-eighths the actual 
fuel value of pure carbon. 

Owing to the absence of smoke and soot, coke is indicated as 

a most suitable oven fuel. In burning it does not choke flues 

or deposit a layer of soot, which prevents the passage of heat 

« 

to an oven. Coke has in burning one property which must be 
reckoned with, and that is that the heat produced is intensely 
local. In consequence the furnace itself may be very hot in 
comparison with the flues at some little distance. Therefore it 
becomes necessary to be careful in designing, so that there 
shall be ready transmission of heat; but with proper arrange¬ 
ments this difficulty is overcome and coke as a fuel provides 
a perfectly efficient method of heating ovens. 

Combustion of Coke. 

A very characteristic property of coke in the act of burn¬ 
ing may be well explained here. Coke or carbon burns flame- 
lessly, and yet over a coke fire one usually sees a play of pale 
blue flame. This is due to the intermediate production of 
carbon monoxide in the combustion of carbon. Let us see what 
is taking place in a good coke fire. At the top there is red hot 
coke burning, in a current of excess of air passing over its 


157 



BREAD-SHOP PRACTICE 


surface. The reaction may be represented by the equation: 

C + O 2 “ CO 2 
Carbon Oxygen Carbon Dioxide 
This is a flameless reaction, and is only visible by the intense 
incandescence of the burning coke: 

There is also, however, another action going on. Air passes 
up through the Are bars and also through the glowing mass of 
coke. In this part of the fire the coke is in large excess over 
the oxygen, and consequently carbon monoxide is formed by 
the partial combustion of the carbon. This reaction is repre¬ 
sented by: 

2C + 02= 2 CO 

Carbon Oxygen Carbon Monoxide 
The carbon monoxide rises to the surface of the fire, when 
it meets with additional oxygen and burns to the dioxide 
according to the following: 

2 CO +02= 2 CO 2 

Carbon Monoxide Oxygen Carbon Dioxide 
It is this secondary burning of the monoxide which causes 
the pale blue flames. Should the supply of air over the surface 
of the fire become inadequate, the carbon monoxide finds its 
way up the flues unconsumed. There may thus occur a very 
serious loss of heat, and this is best realized by studying the 
heat of combustion of carbon and carbon monoxide, respect¬ 
ively. One gram of carbon on burning produces 8,080 heat 
units, while the same quantity of the latter yields 2,634 units. 
From the equation given above it may be easily calculated that 
1 gram of carbon forms 2.33 grams of carbon monoxide, and 
this quantity on further burning yields: 

2.33X2,634=6,146 heat units. 

But as 1 gram of carbon yields 8,080 heat units, we have 
8,080 — 6,146 = 1,934 units produced in the burning of 1 gram 


of carbon to monoxide. Consequently: 

Heat produced by 1 gram of carbon burning to 

monoxide. 1,934 

Heat produced by the combustion of the carbon mon¬ 
oxide yielded by 1 gram of carbon. 6,146 


Heat units . 8,080 


158 








BREAD-SHOP PRACTICE 


Whatever quantity therefore of carbon monoxide which 
escapes combustion means a loss of over three-quarters of the 
heat-producing power of the carbon it contains. Due provision 
must therefore be made for admittance of air to the coke gases 
after they have left the coke. 

Steam in Furnace. 

It is a widely spread idea among furnace men that the air 
which feeds a furnace fire through the fire bars is all the better 
for being charged with water vapor. The view is that the 
requisite amount of heat is thus produced from a less amount 
of coke. In order to produce this effect vessels of water are 
frequently placed in the ash pit, and patentees have gone 
further by inventing hollow fire bars into which steam is in¬ 
jected. There is very considerable evidence in favor of this 
introduction of water vapor being advantageous. One result 
is probably that it keeps the fire bars comparatively cool. 
When the bars get very hot they are likely to clinker, and 
clinker consists of a compound of siliceous matter from the 
coke with the iron of the bars. The production of this body 
obstructs the draught of the furnace and in that way cools and 
lessens the efficiency of the fire. Anything therefore which 
obviates this is an advantage. Attention is drawn to this 
introduction of steam for another reason. When steam passes 
into red hot coke it is decomposed with the liberation of hydro¬ 
gen, thus: 

H 2 O -h C -f CO 

Water Carbon Hydrogen Carbon Monoxide 

A little knowledge is a dangerous thing, and some chemical 
students have said: Look, here we have hydrogen formed in 
this manner, and therefore in this way there is an additional 
source of furnace heat due to the subsequent burning of the 
hydrogen thus formed. But any such reasoning omits to take 
cognizance of the fact that the heat generated by the com¬ 
bustion of this hydrogen is exactly counterbalanced by the 
heat absorbed in the original decomposition of the water into 
free hydrogen and oxygen by the effect of the carbon. There 
is therefore no actual outside production of heat from these 
changes which the water undergoes. 


159 



BREAD-SHOP PRACTICE 


Producer Gas. 

At this stage some mention may be made of a method of 
making gas from coke for oven heating purposes. A well- 
known process is employed in gas works for the manufacture 
of what is known as water gas. Air is forced through a ves¬ 
sel containing red hot coke until it is in a state of intense in¬ 
candescence. Steam is then passed with the production of 
hydrogen and carbon monoxide in equal volumes according to 
the equation just given; and this mixture, usually enriched 
by the gaseous products of heat-decomposed oil, is utilized for 
illuminating and heating puiposes. Such gas may be employed 
for the heating of ovens. But in this direction another reac¬ 
tion is more frequently employed. A container called a pro¬ 
ducer is used; this is charged with coke which is lighted and 
allowed to bum until the whole mass is red hot, the products 
of combustion being allowed to escape through the chimney 
stack. The gas is then directed to the ovens, and set fire to 
in the furnaces. By regulation of the draught, air is di’awn 
through the producer and then carbon monoxide is formed 
thus: 

2C + 0, = 2C0 

Carbon Oxygen Carbon Monoxide 

The supply is controlled by governing the current of air. 
This form of heating lends itself well to the firing of steam 
pipe ovens. A whole group may be fired from one producer. 
The advantages are that the furnace arrangements of the 
ovens are very simple, and that they require no stoking. Con¬ 
sequently the wear and tear on the ovens is very small, and 
with clean gas there is very little choking of flues by soot or 
dust. 

Distribution of Heat. 

Everyone knows that a fire makes a room warm, boils 
water, and in other ways satisfies our requirements in the 
matter of raised temperatures. But not everyone is so clear 
as to how this distribution of heat takes place. That it can 
proceed over enoimous distances is illustrated by the effects 
produced by the sun’s heat over 95 millions of miles away. 
Nevertheless the baker, and still more those who have to pro¬ 
vide many of his appliances for him must study the prob- 


160 



BREAD-SHOP PRACTICE 


lem very closely. For example, it would never do to have an 
oven in which the bread was burned to a cinder over the fur¬ 
nace and remained stone cold at the further end. Heat is 
distributed in three distinct ways, of which a description 
follows: 

Convection of Heat. 

This is the very simplest mode of distribution and results 
from the actual transference of the heated substance from 
place to place. Such moving hot matter mingles with that 
which is colder, and so gradually warms the whole mass. The 
principal way in which the hot material is set in motion is by 
its expansion and consequent diminution in gravity. The boil¬ 
ing of a pot of water is one of the best examples of this; or 
still better a flask of water, because in the latter it is easy 
to make the movements of the water visible. Let such a flask 
of water, of, say, a quart capacity, be taken and a few grains 
of litmus dropped in. It will be remembered that litmus is 
the blue coloring matter used as an indicator in acidity testing. 
The litmus sinks to the bottom. On placing the flask over a 
burner the water at the bottom gets hot and dissolves some 
of the litmus. With getting hot it expands, and owing to its 
greater lightness ascends through the heavier layer of cold 
water, which latter falls to the bottom and replaces it. The 
movement of the water upwards is very plainly shown by the 
blue coloration of the litmus. Little currents ascend towards 
the surface, and gradually get dispersed, until the whole liquid 
becomes of an even blue and also an even warmth. A very 
simple but nevertheless striking experiment consists in taking 
an ordinary 6-inch test tube, filling it with cold water, and 
heating the lower end in a small flame. Holding it at the top 
between the fingers, it is felt almost immediately to get warm. 
On passing them down the tube it is all felt to be practically at 
the same temperature. Now re-start the experiment, only 
hold the tube in the fingers at the bottom, and apply the heat 
at a point half way up; the upper part of the water boils while 
the bottom remains quite cold. Convection, then, means a 
conveyance of heat by actual transference of the heated sub¬ 
stance from place to place, and usually by its becoming lighter. 

The general lesson to be learned from convection as a mode 
of heating water is that the source of heat should be placed 


161 




BREAD-SHOP PRACTICE 


as low as possible. An interesting complementary problem to 
that of heating a vessel of water is that of cooling same. Men¬ 
tion has already been made of the fact that the attemperating 
tank in a bakery is often advantageously fitted with an ar¬ 
rangement for cooling by the action of ice. It has been 
stated in these articles that this should consist of a perforated 
tray for the ice fixed at the top of the tank. In popular par¬ 
lance, people sometimes say that heat ascends whereas cold 
descends. A word of warning may be given as to mental 
images in which heat and cold are regarded as two opposing 
forces or entities. Cold is a purely negative quality, and only 
means the absence of heat. Similarly, some people speak of 
light and darkness as two opposing forces, whereas darkness 
is only the absence of light. It is not a generally known fact 
that Goethe, the great German poet, also took an interest in 
science. He enunciated a theory that there were two separate 
things or entities called Light and Darkness. Further, he be¬ 
lieved that all colors simply consisted in mixture in various 
proportions of these two properties. One of the present 
author’s earliest professional commissions was to make a 
series of experiments in support of Goethe’s theory. Unfor¬ 
tunately for the hypothesis, they failed to adduce any proof of 
same. 

To go back to our problem of ice cooling: Suppose the water 
is at 80 degrees Fahr., and ice placed in the tray at the surface. 
The water in touch with the ice is at once cooled, contracts, 
and becomes heavier; in consequence it sinks, and the warmer 
water rises to take its place. It is not difficult to see that in 
this way the whole mass of water gets evenly cooled. 

On the large scale, world-wide climatic efforts are produced 
by the action of convection. The Gulf Stream is due to the ex¬ 
pansion of parts of the ocean by heat, the hot water flowing 
outward and cold water returning to take its place. The con¬ 
figuration of the land largely determines what regions shall 
be enveloped in the warm stream of water proceeding north, 
the fortunate ones being blessed with an equable climate; those 
not so favorably placed suffer all the rigors of an arctic win¬ 
ter. Similarly, the great air currents, known as the trade 
winds, are largely convection currents of hot air caused by 
the tropical sun’s rays. 


162 




BREAD-SHOP PRACTICE 


Draughts, Chimneys and Chimney Pots. 

To come to a more immediate point, convection plays an 
important part in problems of furnace draught. Air is heated 
by a fire, it expands and becomes lighter, consequently it 
rises and a current is thus established through the furnace. 
For precisely similar reasons, hot air currents are maintained 
through the various flues of an oven. A word on the effect of 
chimneys may here be inserted. One has only to get in touch 
with stokers and other furnace or boiler men to know that a 
tall chimney produces a draught. It is well to learn why this 
is. Take the case of an ordinary chimney. The hot air from 
the flame of the fire may well be less than half the density 
of cold air; consequently it rushes up the chimney in virtue of 
the downward pressure of the cold surrounding air—and this 
is* called ‘"draught.” But why should a very tall chimney in¬ 
crease draught? This is largely governed by the difference 
in density between the outgoing and incoming air, but this is 
not materially increased by the length of the chimney. The 
probable reason is that in virtue of the greater length of 
chimney, the pull of the rising current is effective for a longer 
time and so a brisker draught is maintained. 

A question which here arises is the somewhat familiar one 
of increasing draught by the addition of a “chimney pot.” 
Very probably this occurs more frequently in the case of the 
heating of private houses than with bakeries; but notwith¬ 
standing this there are cases where the chimney pot problem 
affects bakers. Now, let us suppose an instance. There is a 
sluggish draught and a chimney specialist recommends a 
chimney pot. The chimney flue is 14 inches square, and on 
the top of this is mounted a circular pot 9 inches in diameter. 
The specialist points in'triumph to the brisk current of air 
through the pot and claims to have cured the trouble. But 
let us see. The sectional area of the square flue is 14"X14"= 
196 square inches. That of the circular pot is 9X9X0.7854=63.6 
square inches. If the current of air is maintained at the same 
rate as before through the flue, it must necessarily travel at 
more than three times the pace through the pot to preserve 
the same volume of chimney uptake. But supposing the air 


163 





BREAD-SHOP PRACTICE 


is passing at only twice the rate through the pot, this will 
seem a material improvement in draught, and yet the total 
uptake of the chimney will have been reduced to approxi¬ 
mately two-thirds. The effect of chimney pots and elongated 
chimneys of diminished sectional area must therefore be care¬ 
fully considered. 

Conduction of Heat. 

Here a somewhat more difficult problem arises. Take an 
ordinary iron bar, a poker if you like, and place one end in a 
fire or furnace. After a time the other end gets warm. This 
is a conveyance of heat by “conduction.’' Let us try to imagine 
the process. Heat has been described as a “Mode of Motion.” 
When a body is cold its particles are comparatively quiescent, 
when it gets hot they become violently agitated. This hot 
condition is quickly caused in the end of a poker in the fii»e, 
and the hot particles there in their agitation knock up against 
their neighbors. These in turn are set in a state of agitation, 
in other words, they become hot. This action goes on until 
gradually, as a result of each particle knocking up against its 
neighbor, the state of agitation reaches the other extreme 
end of the bar, which gets hot. Conduction of heat may there¬ 
fore be regarded as that method of transmitting heat in which 
the positive motion of hot particles is communicated to the 
colder ones lying in actual contact and thus in turn makes 
them hot, and so transmits heat through the whole body. 

Let us enlarge our experiment by using a bar each of iron, 
copper and glass, as before, so that each is of the same size, and 
placed in the same fire or other source of heat. The iron will 
warm at the far end as before, but the copper will get warm 
about seven times as quickly as the iron, while the glas.^ wdll 
probably remain to the senses quite cold. (Glass in fact con¬ 
ducts heat at about one-tenth the speed of iron.) This means 
that the particles of copper are much more sensitive to the 
knocks of adjacent particles than are those of iron, while the 
particles of glass are much less so. This difference has led the 
grading of bodies into good, medium and bad conductors of 
heat. The metals generally are good conductors, though they 
range from silver, with a conductive power of 100, down to 
lead, with 8 only. Clay and bricks therefrom are bad con- 


164 





BREAD-SHOP PRACTICE 


ductors; so also are glass, air, water, and woolens. Where it 
is required to retain heat, as in the case of an oven, this end 
is attained by the use of brickwork. A very useful form of 
heat retainer is a layer of mineral fibrous matter, such as loose 
asbestos or slag wool. This material in itself conducts heat 
badly, and this property is much enhanced by the badly con¬ 
ducting air contained in its interstices. A cavity wall therefore 
with slag packed in the cavity serves well to retain heat, and 
this method of building can be used with good effect in the case 
of ovens. 

Ordinary clothing is another illustration of the non-con¬ 
ducting effect of the air entangled in fibrous or cellular ma¬ 
terial. If an ordinary cloth suit, which is fairly porous, could 
be compressed into a thin air-free layer its warming (i. e., non¬ 
conducting) properties would be seriously diminished. Where, 
on the other hand, rapid transmission of heat is desired, metal 
is employed where possible. Thus we have iron or steel steam 
boilers and copper kettles. When water containing mineral 
salts, especially carbonates and sulphates of lime and magnesia, 
is boiled, these are deposited as a coating of 'Tur'" on the in¬ 
side of the boiler. This fur conducts heat extremely badly, 
and so very seriously diminishes the efliciency of the boiler. 
Boilers, etc., should therefore be kept as clean inside as pos¬ 
sible. 

In passing, it may be mentioned that not only are bricks 
bad conductors of heat (or good non-conductors as they are 
sometimes called), but they are also very difficult to melt, the 
degree of difficulty largely depending on that of purity of the 
clay. Furnace or fire bricks are made from specially refractory 
(or fire resisting) clay. 

Radiation of Heat. 

So far, we have been dealing with the transmission of heat 
through actual matter, but there is another phase of trans¬ 
mission and that is where it is through space devoid of matter, 
or by some agency other than matter in space in which matter 
is present. Proof of the existence of such transmission is af¬ 
forded by the fact that we get essentially all our heat from the 
sun, although that body is some ninety-five millions of miles 


165 



BREAD-SHOP PRACTICE 


away, and the intervening space is devoid of matter in the 
sense in which we use that term. The modem view is that all 
space is filled with an elastic medium called “ether,” which 
possesses no weight and therefore is not matter in the strict 
sense. (To be absolutely correct, this hypothesis has been 
attacked during the last few months by a German physicist 
who alleges that a ray of light is deflected from its straight 
course by the influence of a contiguous body. Measurements 
have been made during an eclipse, and it is stated that such a 
ray is bent by passing close to such a body as the earth. Should 
this be so, the vehicle by means of which light travels must be 
subject to' the action of gravitation, or in other words must 
ix>ssess weight. The point is still far short of deflnite proof, 
and in any case ether may be regarded as either possessing 
no weight or, in the alternative, weight in an inflnitesimal 
degree.) The action of this invisible ether may perhaps be 
best realized by taking as an example another body possessing 
analogous properties, i. e., water. The following is an experi¬ 
ment which every one has made, still it is worth doing again. 

Select a smooth and still pond and throw a stone in it. At 
once a series of waves start from the point of impact and 
travel outwards in a series of ever-expanding circles. Next 
throw in a cork or small piece of wood, and again a stone a 
few feet from it. Tlie waves rapidly approach the cork, which, 
however, only bobs up and down, and otherwise remains sta¬ 
tionary while the wave proceeds onwards in its course. A 
wave is therefore a transmission of motion from one place to 
another, without a corresponding transmission of the particles 
of the body through which it passes. It will probably simplify 
matters to the student if he is at once told that heat and light 
are closely allied in this respect. Most of the more important 
laws were discovered and worked out in the case of light, but 
were found also to apply to heat. 

Suppose that in the ether of space two meteoric bodies 
clash together; intense heat and light are at once generated. 
Then waves are started in the ether somewhat like those in¬ 
duced in water by the fall of a stone. These spread in ever- 
widening circles, or rather spheres. For not only do they 
diverge horizontally, but also vertically and in every other 

166 




/ 





BREAD-SHOP PRACTICE 


direction. The particles of ether move up and down in trans¬ 
mitting this wave of light, but they also move to and fro in 
every other direction. This condition of things is expressed in 
the statement that the undulations of a wave of light or heat 
are in a plane transverse to the path of the ray and that the 
ether particles vibrate in every direction in that plane. To dis¬ 
entangle this completely requires more knowledge of high 
mathematics than can fairly be expected of the student, still, if 
he will fix first in his mind the water-wave image, and then the 
sudden-light idea, with the realization that in the middle of 
the ether there is no reason why the particles of the light 
waves should undulate up and down more than in any other 
direction, he will figure something to himself that will give him 
a mental vision of a wave of light and heat. If you single out 
a small portion of such a wave you get a line of light which is 
usually spoken of as a ray. Such a ray consists of a beam 
of light traveling in a straight line, and may be regarded as 
moving in virtue of oscillations or undulations in the ether in 
all directions transverse (at right angles) to the direction of 
the ray. 

But we have not yet done with all the possibilities of our 
wave experiment. Throw in a big stone, the water is trans¬ 
formed into waves of considerable depth or height; then next 
they are a good length from crest to crest. Throw in a 
small stone, the waves are small and the length from crest to 
crest is short. All this has its analogue in the case of light. 
On the clash of our two meteoric stones, the light and heat 
not only start out through the ether in waves, but further in 
waves of different lengths, i. e., from crest to crest. A com¬ 
posite wave of lengths between certain limits produces the 
sensation of white light when it impinges on the eye. An 
analysis of that composite wave shows that it is partly built up 
of comparatively short length waves, and these if separated 
from the others give the eye sensation of blue. As the length 
gets longer, the eye sensation changes through a scale of green, 
yellow, and orange down to red. In other words, you have all 
the colors of the spectrum. 

Smaller waves than the blue, and longer waves than the 
red, do not visually affect the human eye, but still there is no 
doubt they exist. In fact, photographic plates are prepared 


167 




BREAD-SHOP PRACTICE 


which are sensitive to waves that are totally invisible to sight. 
Among these are the heat waves, which are of greater lengths 
than those of light, but on the whole are governed by the same 
laws. Their genesis may be regarded from another angle. 
Put a bar, say of iron, in a powerful Bunsen flame; it gradu¬ 
ally gets hot. If the hand, or a suitable thermometer, be placed 
near they both detect the effect of warmth. The iron is setting 
up in the ether long length waves of low intensity. Gradually 
shorter and also more vigorous waves are formed, and the 
near hand feels that the heat being evolved is greater. Still 
continue the application of heat, at last the iron gets dull red- 
hot; that is, on the heat waves have been superposed the 
shorter red-light waves, and hence the emanation of light. 
On further heating the iron becomes white hot, that is, it sets 
up in the ether waves of all the lengths which, on being blended 
together, induce the visual sensation of white light. The nar 
ture of light waves has been explained thus fully because they 
are governed by the same laws as the waves of heat, and the 
former are most easily obseiwable, in virtue of their vis¬ 
ibility. Rays of light can be reflected, refracted, and focussed, 
and so can those of heat. • 

Good and Bad Radiators and Absorbers of Heat. 

But what is more important for our purpose is the nature 
of the property which governs the power of emanation of such 
rays on the one hand, and their absorption on the other. If 
in a dark room a ray of light is allowed to enter through a 
hole in the window shutter, and a mirror is placed in the path 
of this, the ray can be reflected in any direction. If instead 
of a mirror a surface painted a dead white is used, there is 
very little reflection of the unaltered ray, but the light is scat¬ 
tered in all directions and the general interior of the room is 
illuminated. If a surface is next taken w^hich has been 
painted a dead black, there is no reflection of the whole ray, 
nor is there a scattered reflection such as with the white 
surface. Instead the light is said to be absorbed. The energy 
of the impinging waves has been transformed into motion of 
the particles of the body itself. 

Again there is the corresponding heat function. Heat 
which has been radiated from a hot body, on striking against 


168 



BREAD-SHOP PRACTICE 


bright and highly polished surfaces is in large amount again 
reflected. With a dull surface there is little such reflection, but 
comparatively high absorption. Consequently the latter be¬ 
comes hot, and the former body remains cool. This leads to 
the classification of substances into good and bad absorbers 
of heat. Further, bodies which are good or bad absorbers are 
also good or bad radiators of heat. The metals, especially 
when highly polished, are bad radiators and absorbents, while 
lampblack and soot are good radiators; so also are hot sur¬ 
faces of clay and brick. The relative power of radiation is 


given in the following table: 

Lampblack (soot), and white lead, each.100 

Tarnished lead. 45 

Polished iron. 15 

Burnished silver. 2.5 


Therefore a bright silver teapot keeps the tea hot in virtue 
of its badly radiating polished surface. The soot-covered 
kettle, on the other hand, gets hot more quickly as the result 
of exposure to radiant heat than it would do if brightly pol¬ 
ished. 

Transmission of Heat in Steampipe Oven. 

An interesting illustration of these various methods of 
transmitting heat is afforded by the steampipe oven. Con¬ 
vection currents occur in the furnace; the heat is thus con¬ 
veyed to the end of the pipe. It passes through the metal by 
means of conduction and heats the water, when again convec¬ 
tion currents are set up. The heat is transmitted to the out¬ 
side of the part of the pipe which is in the oven by conduction. 
Then by radiation the heat is disseminated through the whole 
of the interior of the oven. Most bakers will tell you that bread 
bakes badly in a new bright tin pan. Consequently they gen¬ 
erally bake the empty new tins very thoroughly before actually 
using them. The explanation is that the bright surface is a 
bad' absorber of heat, but as soon as tarnished the heat is 
absorbed much more readily. Therefore the dull tins are the 
better bakers. 

Among modem oven fittings, there is usually found a ther¬ 
mometer or pyrometer for the purpose of measuring the tem- 


169 








BREAD-SHOP PRACTICE 


perature of the interior of the oven. The thermometer is of 
the mercury type and needs little further explanation. The 
baking temperature of an oven runs rather near to the point 
at which liquid mercury becomes uncertain in its behavior, 
and so a special kind of thermometer is generally adopted. In 
the ordinary instrument, the space above the mercury is usu¬ 
ally a vacuum, but in the special high temperature type this 
space is filled with nitrogen, and in this way the effective range 
of the thermometer is increased. The nitrogen exerts a definite 
pressure on the mercury and so raises its boiling point. On 
the other hand, because of its neutral character it exercises 
no chemical action on the mercury. 

The Pyrometer. 

Literally this means a “fire-measurer,^^ and the name is 
applied to a number of instruments devised for measuring tem¬ 
peratures beyond the range of the mercury theimometer. 
Those employed in ovens depend on rates of unequal expansion 
for various materials. Thus if a rod of comparatively inex- 
pansible mateiial is inclosed in a metal casing, with the two 
fastened together at the one end, then as the result of increase 
of temperature the metal casing becomes the longer, and this 
increase is registered on a dial, by means of clockwork, as 
degrees of temperature. The same end is attained by riveting 
together throughout their length two strips of unequally ex¬ 
panding metals. These lie perfectly straight when cold, but 
as the result of heating and unequal expansion the compound 
bar becomes curved. Again the effect is registered in terms 
of temperature on a dial. 

Most pyrometers of this kind are somewhat irregular in 
their action, and cannot be depended on to register the cor¬ 
rect temperature of the oven. The best thing to do is to note 
where the index finger of the instrument is when the oven is 
baking correctly. Then when the oven is heated until this 
point is reached, it will generally be found to be at the desired 
baking heat. 

A word of caution may be given as to both thermometers 
and pyrometers. However correct these instruments may be, 
they can only register the actual temperature of the air in the 
interior of the oven. Now, supposing an oven is fired very 


170 



BREAD-SHOP PRACTICE 


briskly, in a comparatively short time the oven will reach the 
baking temperature as shown by the thermometer. On the 
other hand, let the oven be heated very slowly, and it will be 
quite a time before the same degree of temperature is reached. 
The baking condition of the oven is not, however, the same in 
the two cases. In the latter, the walls and general substance 
of the oven will be much more thoroughly heated. In other 
words, the oven will be much more ‘"solid.” This is at once 
shown on baking a batch—in the solid oven the temperature 
goes back but slowly. In the more superficially heated oven, 
there is a slump, and the temperature falls badly. Therefore 
the thermometer or pyrometer must be read in the light of the 
nature of the previous heating of the oven, whether rapid or 
slow. 

Summary. 

Operation of baking: Earlier methods, and primitive types 
of oven. 

The side-flue oven, intermittent heating and baking; merits 
and defects. 

External flue ovens; importance of the principle of con¬ 
tinuity. 

Steam pipe ovens: Principle of corresponding increases 
of pressure and temperature. 

Steam pipe ovens, heated by circulating pipe, afterwards 
by single pipes. General construction. 

Heat Problems: Sources of heat, the sun, inflammable 
substances; wood, coal and products therefrom. 

Combustion, and heat produced during. 

Coke and its combustion, production of carbon monoxide. 
Division of total heat into the two stages of oxidation. 

Injection of steam into furnace. Effects of fallacious view 
of result of burning of hydrogen. 

Producer Gas and its employment in relation to the heating 
of ovens. 

Distribution of heat, first by means of convection. 

Convection of heat, and its effects in the oven furnace. 

Draughts, chimneys and chimney pots. 

Conduction of heat; good and bad conductors. 

Radiation of heat, analogy between heat and Light. 


171 


( 



BREAD-SHOP PRACTICE 


Reflection of light and heat. 

Good and bad radiators and absorbers of heat. 
Illustration of various modes of transmission of heat in a 
steampipe oven. 

Oven thermometers and pyrometers. 


172 



CHAPTER XI 

THE BAKERY LABORATORY 

This is a very fascinating subject, and one on which the 
author is being continually asked for advice and suggestions. 
In trying to comply with this request, there is first of all the 
mammoth bakery having an enormous output. At the other 
end of the scale is the very small baker, working practically 
singlehanded. The former can do in the laboratory way what¬ 
ever is desirable, and the proprietor does wisely to secure a 
thoroughly capable chemist, pay him well, and take his advice 
as to what is requisite and necessary. The latter can do little 
or nothing, and any suggestions to him as to how he may rig 
up a laboratory would be simply tantalizing. Between them, 
however, is the great middle class consisting of the men who 
are able and wishful to do something, and yet must consider 
ways and means and what results can be attained. It is for 
this class that the following suggestions are made, and even 
in their case the individual differences are so great that any¬ 
thing advanced must be regarded as somewhat tentative in 
character. 

Position and Fittings of Laboratory. 

The first object should be to decide what extent of flour 
testing and other similar work is to be done, and then next 
what amount of space is available for the purpose. If at all 
possible some room or some portion of a room should be spe¬ 
cially reserved for this work. With any choice at all, a room 
should be selected near the bakery and with a fairly equable 
temperature. Failing this, a portion of an office may be de¬ 
voted to this work. In any case, the place selected should be 
reasonably quiet and such that apparatus and tests may be 
left secure from disturbance. But no one can tell so well as 
the worker himself what are his best arrangements in his 
own particular surroundings. A working bench may be fixed 
firmly against a wall, in which case it may be twenty inches 
wide and thirty-three inches high. Gas should be laid on, 
with bell-nose taps over which India rubber tubing can be 
slipped so as to connect up Bunsen burners for heating pur- 


173 


BREAD-SHOP PRACTICE 


poses. There should also be a sink or drain provided, and 
this may very conveniently be a foot square by eight inches 
deep, and constructed of porcelain ware with a plug in the 
bottom. A cold water tap should be fixed over it sufficiently 
high to fill bottles and such flasks or jars as are used in the 
laboratory. The height may very well be eighteen inches 
in the clear from the bottom of the sink. Such a sink with 
the plug in makes a very convenient vessel of water for many 
laboratory purposes. If hot water is available, a similar serv¬ 
ice tap for same is a great acquisition. 

A table may be used instead of the bench, but in that case 
it should be firmly fixed, and should be higher than the usual 
height of a table. 

The light in any case should be good, and shelves should 
be arranged on the wall to take apparatus. 

Baking Tests. 

Whatever else is done, baking tests are sure to be made 
in the bakery laboratory. The first thing in these is to de¬ 
termine the method to be adopted, and usually the wisest 
course is to follow as closely as possible the general process 
or processes used in the bakery itself. The baking test should, 
in fact, be a miniature reproduction of the bakeshop opera¬ 
tions. 

The barrel of 196 pounds being the general unit weight 
of flour, it is very convenient to take laboratory quantities on 
that basis. For this purpose the gram or metric system is 
very convenient, and 196 grams may be taken. As the ounce 
is equivalent to 28.35 grams, 196 grams are very nearly 7 
ounces. This quantity is too small for most purposes, but 
the double quantity of 392 grams, which thus takes prac¬ 
tically 14 ounces of flour, yields a convenient-sized loaf. Every 
other ingredient is then taken in double barrel quantities. 
To this an exception must be made in the case of yeast, be¬ 
cause proportionately more yeast is required to ferment a 
small quantity of flour than a larger amount. Thus in a batch 
of four barrels of flour, six pounds of yeast may be taken, 
while probably the same baker would take two pounds to a 
batch of one barrel only. This is largely due to the greater 
relative loss of heat from the smaller batch. When it comes 


174 




BREAD-SHOP PRACTICE 




down to less than a pound of flour in each test, the yeast 
requires to be taken in still higher proportions. In making 
baking tests in England, where the sack of 280 pounds is the 
unit, the writer commonly makes a 560 gram test, and with 
that takes 10 grams of yeast. In certain American test 
laboratories, 340 grams of flour are taken, with also 10 grams 
of yeast. Judging from these tests, 10 grams will probably 
be found a convenient quantity for the 392 grams of flour. 
Salt may be taken in the usual bakery amount, which aver¬ 
ages about 3^ pounds per barrel. Sugar is so generally used 
in American bread that it should also be taken in the baking 
test. The simplest thing would be to take the same amount 
as is used in the bakery. This varies in recipes in the writer's 
possession from 1^ to as much as 5 pounds to the barrel. In 
the American test before referred to 12 grams of sugar to 
the 340 grams of flour were taken; this seems a somewhat 
heavy proportion. Even 10 grams to the 392 is at the rate 
of 5 pounds to the barrel, and this is, one would judge, full 
measure. The quantity of sugar is rather important, because 
sugar acts as a yeast food and stimulant, so that a weak flour 
may possibly be helped thereby more than it deserves, and 
consequently judged too favarably. 

Nearly all American bakers use some form of fat in their 
bread; but published American test methods do not always 
contain it, though in the formula of the Howard Flour Test¬ 
ing Laboratory of Minneapolis, lard is included. It may very 
well be, therefore, that in order to judge of a flour under bak¬ 
ery conditions, fat of the usual kind should be added in the 
usual quantity. The baking test formula would then become 
something like the following: 


Flour. 392 grams 

Yeast. 19 grams 

Sugar, say (or quantity actually used). . 10 grams 

Salt, say (or quantity actually used).... 7 grams 

Lard or other fat, say (or quantity actu¬ 
ally used). 19 grams 

Water.A sufficiency 


175 








BREAD-SHOP PRACTICE 


Quantities Used. 

In order to make the test, weigh off 392 grams of the flour 
from a sample which is of the normal bakery temperature. 
This should be done on a balance having a pan capable of 
carrying easily this amount, and sensitive to at least the half 
gram. Transfer this flour to a glazed ware, or enameled iron, 
bowl of convenient size. Next weigh off the yeast, sugar, salt, 
and lard, putting each in a small basin or dish. Take the lard 
first of all and rub it into the flour, taldng care that as little 
as possible is lost on the hands. The sugar and salt may next 
be stirred into the flour. There remain the yeast and the 
water. Of the latter, what is “a sufficiency”? American 
recipes in the hands of the writer give quantities varying from 
105 to 118 pounds of water to the barrel. Here again the 
baker must decide for himself as to the degree of tightness he 
wants in his doughs, and the proportion of water he prefers 
to adopt in actual practice. Let us take 110 pounds per bar¬ 
rel as a convenient figure, then in his test the flour should 
take 110 X 2 = 220 grams of water. But the object of the test 
is to find out, among other things, how much water the par¬ 
ticular flour will take to make a dough of standard consist¬ 
ency. Now water may either be weighed or measured, and 
1 gram equals 1 cubic centimetre (1 c.c.), so that either a glass 
graduated measuring jar may be used, or a beaker in which 
the water can be weighed. A good deal can be said in favor 
of each method, but bakers as a rule seem to prefer the weigh¬ 
ing process. For that the following is a very convenient mode 
of procedure. 

Working Temperatures. 

Procure a glass beaker of, say, 300 c.c. capacity, pour 250 
c.c. of water in it and make a mark, either with a writing 
diamond or some glass-marking ink, on it, to indicate this - 
quantity. Have a counterpoise made the exact weight of the 
dry beaker. These are sold by the apparatus dealer in the 
form of brass boxes with screw-on lids. One of these is taken 
and filled with shot to the exact weight. Before making a 
test, the question of temperature comes in. The following 
are convenient bakeshop temperatures in ordinary working: 
Flour 70 degrees, bake shop 80 degrees, water 84 degrees,. 


176 




BREAD-SHOP PRACTICE 


dough 82 degrees Fahr. The temperatures of flour, bake shop, 
i. e., laboratory, and dough should be about those named, but 
it is well to check them, especially that of the dough, against 
those which in fact obtain in the bakery. It may be taken as 
a general rule that the dough in a small test should be as 
high in temperature as, or possibly a trifle higher than, a full 
size working dough, because the cooling effect of the atmos¬ 
phere is usually greater on a small batch. Further, the loss 
of heat is more in mixing a small test batch than in the case 
of a working dough. This is best settled by a few preliminary 
tests. Mix flour and water in the desired proportions at such 
temperatures as thought desirable and note the temperature 
of the resultant dough. 

By means of such tests, decide what is the required tem¬ 
perature of the water to produce a dough of the standard bak¬ 
ery temperature. Such doughs made for this purpose may, 
if wished, when the desired information is obtained, be thrown 
into and worked up with an ordinary batch of bread. 

Having thus got the desired water temperature, take the 
beaker and All to the graduated mark, or nearly to it, with 
warmed water of the correct temperature. Put the beaker on 
one pan of the balance, and the counterpoise and 250 gram 
weights on the other. Weigh off exactly this quantity of 
water. This is very easily done by adding the last increments 
of water very carefully. If the weight is overshot draw a 
little off with a pipette. The tester now has a known excessive 
weight of water. Add 20 or 30 c.c. of it to the yeast, and break 
it down into a smooth cream. Make a depression in the flour 
and other ingredients in the bowl. In England, this is called 
making a ‘"bay.” Transfer the yeast to this. Next add the 
remainder of the water up to, say, about 220 grams of water, 
and start to make a dough. Now here is where the skill of the 
baker flour tester comes in. It is very difficult to work in more 
water in a too tight dough. Before the mixing is finished the 
baker forms his own estimate of whether the dough is likely 
to be too tight or too slack. Of course the dough must not 
be made too slack, but if right or a little on the tight side it is 
left as it is or a little more water added, as the case may be. 
At first the tester is all at sea over this question, but shortly 


177 



BREAD-SHOP PRACTICE 


there comes a sixth sense by which the tester judges very 
closely the right amount of water to add. This having been 
done, the dough requires to be mixed and the residual water 
must be weighed. The original weight less that of the remain¬ 
der is the amount which has been used in making the dough. 

Machine Versus Hand Kneading in Such Tests. 

Then next there is the mixing or kneading. The chemist 
as a maker of baking tests usually elects to mix in a kneading 
machine, since in fact kneading by hand conveys nothing to 
him. The baker, on the contrary, likes to know how the dough 
feels, and hence favors hand kneading. The present writer, 
as an old chemist, who has perhaps learned to appreciate some¬ 
what the taker’s touch,” leans rather to the baker’s view. In 
tests which are made by the baker in a baker’s laboratory, 
hand kneading is almost certain to be adopted. Assuming that 
to be decided on, the mixing must be thoroughly done, and the 
tester should observe carefully the way in which the hour 
makes up. Particular attention should be paid to whether the 
dough is elastic, springy and dry, or whether it is soft, lifeless 
and sticky. Its general behavior should be noted, and whether 
when made it is of the right consistency or either too slack or 
too tight. 

The total weight of dough is of course the sum of that of 
the constituents, and supposing 220 grams of water have been 
taken, the figure will be 392+10-1-10+7+10+220=649 grams. 
That is, 

649 

there are —— =3241/2 pounds of dough from a barrel of flour. 

Li 

After allowing a reasonable amount for loss during fermenta¬ 
tion, this figure may be taken as a guide' to the yield of the 
flour. 

Having made the dough, the next step is its fermentation, 
and this may very well follow as closely as possible the times 
and methods of the actual bakery. 

A Practical Proving Cupboard. 

It is well to provide a proving cupboard for this part of the 
operation. Such a cupboard may conveniently be made of 


\ 


178 




BREAD-SHOP PRACTICE 


sufficient size to take simultaneously six tests, say three on a 
shelf. Whatever the size of the dough bowls, the depth of the 
shelf (back to front) should be two inches more than the out¬ 
side diameter of the bowl. The length of the shelf (width of 
the cupboard) should be three times that diameter, plus an 
extra three inches for clearance. Two such shelves would take 
the six tests, and there should be three inches in the clear 
between the bottom of the shelf and the top of the bowl under¬ 
neath. If found more convenient, three shelves, each for two 
bowls, may be taken instead. The shelves themselves should 
be made of stout wire gauze, or other material which allows 
free circulation of air. The cupboard itself should allow at 
least a foot, and preferably eighteen inches, between the 
lowest shelf and the bottom of the cupboard. A small hori¬ 
zontal ring gas burner should be fitted on the floor of the cup¬ 
board, and thereon a shallow metal vessel should be placed, 
containing water. A thermometer should be fixed at the top of 
the cupboard, so as to regulate the temperature. For this 
purpose a hole may be bored through the wood and the ther¬ 
mometer fixed in position by being passed through a cork. By 
trial the burner should be arranged so as to maintain a con¬ 
stant temperature of say 80 degrees Fahr. in the cupboard. 
Two or three small holes should be bored through the door at 
the bottom, and corresponding ones through the top of the 
cupboard at the back, so as to provide for a slow current of air 
through in order to enable the gas of the burner to bum. The 
reason for having the considerable space between the burner 
and the bottom of the bottom shelf is to prevent the lower 
shelf being heated appreciably more than the upper one. In 
any case there is a tendency that way, and it may be partially 
prevented by fixing a baffle shelf say six inches below the 
lowest other shelf. This baffle shelf may be of wood, with a 
number of inch holes about four inches apart. 

With this arrangement in good working order all loaves 
will be fermented in a moist atmosphere at a fairly constant 
temperature. The bowls should be kept covered with a folded 
piece of flannel in order to further ensure regularity of tem¬ 
perature. Whatever time is decided on for the whole fer¬ 
mentation, say three, four or five hours, as the case may be, 
then within an hour of the close the loaves should be taken out 


179 





BREAD-SHOP PRACTICE 


and rekneaded. Notice carefully the volume of the 
loaves when taken out, and their behavior when 
handed up. Particular notice should be given to their 
resiliency or springiness, whether sticky or the re¬ 
verse, and generally to the working qualities of flour. At 
this stage a judgment should be arrived at as to what quantity 
of water the flour takes and how it holds it. Having moulded 
the dough return it to the cupboard as before, let it prove for 
about half an hour, then gently mould up again and place in a 
tin or pan; let prove in that for twenty to thirty minutes again 
in the cupboard, and the loaf should be ready for baking. Tt 
may then be weighed if wished. This will be done in the tin, 
and the weight of the tin being known, that of the dough can 
very easily be ascertained. The weight of dough in grams di¬ 
vided by two will give the weight in pounds of fermented 
dough per barrel of flour. Occasionally there will be found 
flours which are unusually rapid or unusually slow in fer¬ 
mentation ; these should be duly noted and their behavior pro¬ 
vided for in the regular bake shop work. Probably this irregu¬ 
larity occurs more frequently in England than in America, be¬ 
cause in England sugar is not often used in the dough. Fer¬ 
mentation must in that case depend on the natural sugars of 
the flour, or those produced by the saccharification of its 
starch. These if superabundant, or unusually deficient, will 
materially accelerate or retard fermentation. Where, as in 
America, large quantities of sugar are added to the dough, 
there is not as a rule any retardation through deficiency of 
sugar. 

A baker will usually elect to bake his test loaves as a part 
of a full oven batch with his other bread. It is well to select 
a place in the oven where the baking is fairly regular, and one 
or two of the adjoining ordinary loaves of the batch would be 
reserved for comparison. First of all, the trial loaves should 
be compared against those of the ordinary batch for color of 
crust. They may be normal or on the one hand fiery (“foxy” 
as it is sometimes called), or they may be very pale. Foxinoss 
may be due to low grade of the flour, or excess of sugar. Cer¬ 
tain kinds of flour have a tendency of themselves to bake very 
pale, i.e., as the baker says, “they will not take the fire.” The 


180 




BREAD-SHOP PRACTICE 


sugar employed in American baking is usually a preventative 
of this. Paleness may also be due to over-fermentation. The 
next thing is the volume of the loaf. When baked in a tin this 
is obviously directly as the height of the loaf. Many persons 
prefer to bake test loaves as all-crusty loaves, as this has the 
advantage of indicating the boldness of the loaf, which is a 
property quite distinctive from volume. Thus one loaf may be 
flat and ''runny,'' while another is bold and upstanding, 
though the actual cubical contents of each may be the same. 
This is a matter for the consideration of each individual baker. 
The bread should next be cut, and the color and texture of the 
crumb noted. Then next the odor and flavor of the bread 
should be carefully observed. Another property which is 
often of value is the moistness of the loaf, and this too should 
be noted. In districts where bread has to be kept two or three 
days before being eaten it is well also to keep the trial loaves at 
any rate for twenty-four hours, to see whether they keep fairly 
fresh or go dry and chaffy. If several trials are being made 
together, it is well to compare the whole of the loaves and ar¬ 
range them in order of merit. 

Bakers' Marks. 


This leads to a method of valuation which has grown up in 
England, of awarding "bakers' marks" as the result of such 
tests. Thus some such scheme as the following may be 
adopted. 


Properties, 

Maximum 

marks. 

Marks awarded 
to test loaf. 

Color of crust. 

. 10 

6 

Boldness of loaf. 

. 10 

6 

Color of crumb. 

. 10 

8 

Texture . 

10 

8 

Moistness . 

. 10 

9 

Odor.. 

. 10 

9 

Flavor . 

. 30 

25 

Keeping properties .. 

. 10 

8 

100 79 

here are given above a list of the properties of bread with 


181 














BREAD-SHOP PRACTICE 



the maximum marks which may be awarded for each. Then 
the marks in the case of an imaginary test loaf are given for 
comparison. These must of course be decided on the judgment 
of the test baker. 

A loaf which came out at 79 marks would be regarded 
as a very good loaf. But the above apportionment of marks 
would very possibly have to be varied according to the stand¬ 
ard of the locality. In some places flavor and its near con¬ 
geners, moistness and odor, are regarded as the all-important 
things. In others a loaf to sell well must be bold and of good 
color. Again, in a district in which the bread is all eaten 
within twelve hours of being baked, keeping properties are 
of far less importance than where bread is delivered only 
twice a week. The relative proportions of marks must, 
therefore, take these local requirements into consideration. 
This is a thing which the individual baker must decide for 
himself. The advantage of such a scheme of marking is that 
a record can be kept of the results of the test in the case of 
each loaf. These serve as a means of judging and comparing 
various deliveries of flour, though at different times, with 
each other. 

Another point which the baker must instinctively bear in 
mind is the place into which this flour will naturally fall in 
his bakery mixture. Thus, suppose the flours he has already 
got in stock make a good bold loaf, but one which is somewhat 
flavorless and also dry and harsh. If a new flour is exceed¬ 
ingly sweet and moist in character, it will be much valued 
. because it supplies just those qualities which are deficient. 
This is all a matter of the baker’s individual judgment, and 
the student must learn to form a correct judgment on these 
lines as early as possible. 

Valuation of Materials Other Than Flour. 

So far we have been assuming that the baking test has 
been made in order to decide as to the value of a particular 
sample of flour. But there are evidently other matters on 
which a baking test may be of considerable value. These prob¬ 
ably group themselves under two heads: First, valuation of 
materials other than flour; second, comparison of different 
baking processes. 


182 



BREAD-SHOP PRACTICE 


The first case is comparatively simple. As an example, 
let us suppose that the baker wishes to decide whether 50 
cents’ worth of sugar or 50 cents’ worth of malt extract gives 
him the best value in general working. He knows how many 
pounds of sugar he uses to the barrel. Then let him take 
twice that number of grams of sugar for one trial test. If so 
many pounds of sugar cost so much, he can very easily cal¬ 
culate what weight in pounds of malt extract he can buy for 
the same money. It is then very easy for him to take again 
twice the number of grams of malt extract, and thus get into 
two tests the same money value of sugar and malt extract. 
This being done, the test can be carried through on the same 
lines as before and the two loaves compared. It may be that 
one gives far better results than the other; then a second 
test may be made with the better value ingredient cut down 
in quantity, so as to make the two approximate. In this way 
a definite guidance is gained as to the exact saving one in¬ 
gredient may have over the other. The student’s own in¬ 
genuity must guide him in making other tests of like nature. 

Comparison of Different Baking Processes. 

The second testing operation is fraught with somewhat 
more difficulty. Possibly one may wish to compare the ad¬ 
vantages of making a straight or off-hand dough with those 
of making first a sponge with one of the flours in a mixture, 
and then adding the remainder of the flour and water so as to 
form a dough later. Whatever the problem, the first part is 
to make the two trials, one by each of the methods to be 
tested, and then compare the results. The difficulty is that 
with small tests the disturbing influence of very minute quan¬ 
tities affects the conclusiveness of any such results. For tests 
of methods and processes larger quantities are almost a ne¬ 
cessity. The smaller tests may be taken as a guide, but re¬ 
quire to be confirmed by experiments on the bakery scale. 

Apparatus Required.—-BsAance carrying 1,000 grams, sen¬ 
sitive to at least 1/2 gram, with pan large enough to take 400 
grams of flour. Set of weights, 500 grams to 0.1 gram. 
Graduated measure or else 300 c.c. beaker and counterpoise. 
Jug or other larger vessel for mixing and attemperating water. 
Thermometer graduated on stem. Burner, tripod and pan for 


183 



BREAD-SHOP PRACTICE 


heating water. Set of small dishes for weighed quantities of 
yeast, etc. Bowls for dough, say eight. Pieces of flannel for 
covering same. Proving cupboard. 

Other Tests. 

Any adequate dealing with these is rather a subject for 
a larger text-book than the present small introductciy work. 
Probably the best compromise is to follow out our idea of 
sketching in the laboratory requisites, and leaving a descrip¬ 
tion of analytic methods to works on flour and bread analysis. 
The following suggestions are based on this idea. 

Tests already described .—Various tests and experi¬ 
ments have already been described in this book. The 
student can ascertain these by back reference, and 
include the apparatus described in his list of labora¬ 
tory requirements. For example, directions have been 
given as to baking tests for rope. The actual baking is cov¬ 
ered by the instructions just given. For the subsequent in¬ 
cubation of the loaves, a hot-water-jacketed oven is necessary. 
This should be obtained from an apparatus dealer, together 
with the necessary additional accessories. The oven should 
be of copper, and must be fixed on a proper stand over a 
Bunsen burner. As it may be required to keep this oven 
going day and night, the burner should be made a fixture to 
the gas supply pipe, and not simply trusted to a piece of 
india-rubber tubing. The latter is likely to perish and give 
out without waniing, thus causing risk of fire. The oven 
should be fitted with a side water-feed so as to keep it auto¬ 
matically supplied. A thermometer should also be fitted to 
tubulure in the oven. The fittings can be obtained with the 
oven from the dealer. In selecting a place for the oven in 
the laboratory one should be chosen, if possible, in which 
the inside of the oven is fairly well lighted when the door 
is open. 

Color tests .—It is at times advisable to make direct tests 
on the color of flour by means of the slab or Pekar’s test. 
For this small pieces of board, say three by six inches, are 
required, or similar pieces of zinc may be used if preferred. 
Also flour spatula or '^slick,^’ block for compressing the flour 
into a slab, and bowl of water for dipping. 


184 




_ BREAD-SHOP PRACTICE _ 

/ 

Gluten tests ,—The following apparatus will be wanted— 
provision for weighing out flour. The balance already de¬ 
scribed can be made to serve this purpose, but really some¬ 
thing more delicate is almost necessary. If any systematic 
work is to be carried on an analytic balance ian<i set of 
weights ought to be procured. The balance should carry 200 
grams and be capable of weighing to a milligram. A good 
balance is the cheaper in the long run, but a conscientious 
apparatus dealer will advise the student how to make the 
best compromise with his pocket. The weights should run 
from 50 grams to a milligram. Small mixing bowl and bone 
spatula. Glasses in which to stand made-up doughs. Fine 
hair sieve for collecting fragments when washing. Drying 
can be done in the hot-water oven. 

Water absorption tests .—The following additional articles 
will be required: Ordinary 50 c.c. burette graduated into 
tenths. Then 19.6 grams of flour may be taken and mixed 
with water, and every tenth of a c.c. required to make a 
dough of standard consistency will be equivalent to a pound 
of water per barrel of flour. 

Moistv/re tests .—These may at times be of service, and 
will require the following additional apparatus. Six stoppered 
weighing bottles about inches diameter by the same 
height. These must be numbered and balanced, together 
with stopper, against corresponding counterpoises also num¬ 
bered, after being thoroughly cleaned and dried in hot-water 
oven. Ten grams of flour are weighed off into bottle with 
stopper, and both open bottle and stopper placed in oven, dried 
until of constant weight (time can be ascertained by test), 
then the stopper inserted, and the bottle weighed when cold. 

Yeast tests .—For the examination of yeast, a microscope 
is necessary. For the selection of this, the student should 
seek the advice and assistance of an expert friend for this 
purpose, than whom there can be none better than a bakery 
science teacher. A good stand should be obtained, with the 
minimum of eye-pieces and objectives. The stock of these 
can be added to by degrees. Of course glass slips and cover 
glasses, and similar minor appliances, must be procured. 

The strength of gas-evolving power of yeast is at times 
tested in a laboratory. This used to be fairly frequently 


185 





BREAD-SHOP PRACTICE 


adopted on the Continent of Europe, since yeasts were sold 
under a guarantee of capacity to produce a certain quantity 
of gas within a given time under standard conditions. The 
apparatus involved will comprise a water bath fitted with 
temperature regulator, bottle for fermentation fitted with 
leading tube, attached to flask, and graduated measuring jar. 
Other requisites have been already mentioned under some 
of the foregoing tests. 

This is after all only a most hasty glance at a baker^s la¬ 
boratory and what should be aimed at in its equipment. 
Thanks to the enterprise of the Bakers’ Helper, the larger 
work on Bread-Making by the author and his son, Mr. William 
C. Jago, is now again on the market in a revised form, and 
this contains detailed descriptions of many operations which 
are here only dealt with in the most fragmentary fashion. 

This bakery tour must now draw to a close, and the writer 
ventures to say farewell to those student friends who have 
been his companions. He trusts that coupled with a heartfelt 
farewell he may add au revoir. 

Summary. 

The bakery laboratory, position and fittings. 

Baking tests. 

Quantities used. 

Working temperatures. 

Machine versus hand kneading in such tests. 

Continuation of Baking Tests. Proving cupboard. Course 
of fermentation, and points to be observed. Mode of baking. 
Judgment on loaves. Bakers’ Marks. Baking Tests other 
than for valuing flour. Apparatus required. 

Laboratory requisites for other tests. Rope in bread. Col¬ 
or tests, gluten tests, water absorption tests. Moisture. 

Yeast—Miscroscope, and Strength testing. 


X % 

THE END. 


186 



INDEX 


Absorbers of Heat, Good and 

Bad.168 

Absorption of Power by Run¬ 
ning Gear .137 

Absorption Tests, Flour.. .176, 185 
Acceleration of Fermentation.. 96 
Accuracy of Weighing and 

Measuring Essential.141 

Acetic Acid. 106 

— Acid Inhibits Rope.... 113, 120 

— Fermentation.102 

Acidity Inimical to Rope Devel¬ 
opment.Ill 

Acid Salt. 31 

Acids, Bases and Salts. 30 

—, Color Changes Due to.31 

—, Investigating Properties of 32 

Action of Zymase. 60 

Activity of Bacteria Dependent 

on Yeast .102 

Advantages of Electric Motors. 137 
Aeration, Effect on Fermenta¬ 
tion. ...55, 97 

Albumin. 27 

Alcohol, Production of. 52 

Alkalis.32 

Ammonia, Test for. 49 

Analysis, Separation . 21 

An Ingenious Baker's Ther¬ 
mometer.89 

Appliances in Bakery, Mechan¬ 
ical.127 

Applying Knowledge in Practice 88 

Ash in Flour. 30 

Attemperating and Measuring 

Tank.141 

Author's Preface . 7 

Avoid Over-mixing. 71 

Bacterial Bread-making 

Troubles.100 

— Effect on Temperature and 

Slack Doughs.102 

— Organisms, How Introduced.103 

Bacterium Lactis.101 

— Termo, Organism of Putre¬ 
faction.101 

Bacilli.101 

Bacillus Mesentericus Fuscus..l02 

Bacteria.101 

—, Activity Dependent on 

Yeast.102 

—, How Introduced.103, 107 

Bakers' Fuels.155 

— Home-made Yeast . 40 


— Marks.181 

— Raw Materials . 16 

— Thermometer, Ingenious ... 89 
Bakery Chemist Helps, How the 12 

— Cleaning and Sterilizing, for 

Rope.117 

— Engines.128 

—, How Rope Develops in.113 

— Laboratory, The.173 

— Machinery, General .139 

— Malt Products . 57 

— Operations.68 

-, How Science Helps in 68 

— Power Requirements .129 

— Sources of Power.127 

—, Systematic Cleaning of.... 119 

Bakeshop Machinery.127 

Baking and Associated Heat 

Problems.149 

—, Operation of.149 

— Processes, Laboratory.183 

— Tests, Bakery . 67 

— Tests, Laboratory.174 

-, — Quantities.174 

Barm or Bakers' Yeast.38 

Barrel or Sack Hoist.140 

Bases, Acids and Salts. 30 

Belting.136 

Blending of Flour..66, 140 

—, Modes of . 68 

Branny Flours Most Liable to 
Rope. ..109 

Bread, Causes of Sour...107 

—, Effect of Over-kneading... 71 

—, Fatty Ingredients . 62 

—, Moistening Ingredients-63 

—, Mould in.124 

— Moulding and Its Nature.. .144 

—, “Proof" of Dough.146 

—, Rope in .108 

— Scoring .181 

— Souring.103, 107 

Bread-Making Operations. 66 

— Heat and. 75 

— Recipes, Evolution of. 72 

— Troubles, Bacterial.100 

Brewers' Yeast . 38 

British Gum (Dextrim).28,58 

“Budding" of Yeast. 50 

Building Up, Synthesis. 21 

Butyric Acid.106 

— Fermentation.101 


Jago^s Bread-Shop Practice 


187 













































































Calculating Specific Heat of 
Flour. 87 

— Water Temperature for 

Dough Temperature. 89 

Cane Sugar.52, 54, 60, 97 

Capabilities of Yeast. 49 

Care of Engines.129 

Causes of Rope.108, 110 

— Sour Bread .107 

Centigrade Temperature Scale. 79 
Changes in Temperature, 

Sources of.84-86 

— Required for Machine Mix¬ 

ing. 69 

Chemical Terms . 22 

Chemistry, What It Teaches.20, 21 
Chimneys, Chimney-pots and 

Drafts.163 

Cleaning and Sterilizing Bak¬ 
ery, Why Advocated.117 

Cleansing of Bakery, System¬ 
atic.119 

Coke, Combustion of.157 

Color of Crust.180 

— Tests.184 

Combustion, Heat Developed 

During.156 

— of Coke .157 

Comparison of Laboratory Bak¬ 
ing Processes.183 

Composition of Cow’s Milk.... 63 

-Dried Potato . 61 

-Starch and Gluten. 24 

-Sugars and Chemical 

Changes. 54 

-Yeast.48 

Compressed Yeast . 40 

“Comp.” Yeast. 40 

Conditions Affecting Speed of 

Fermentation.♦... .52, 96 

Conduction of Heat.164, 169 

Content of Flour, Fat. 34 

Contents. 8 

Continuous Oven, Principle of. 152 
Controlling Fermentation Fac¬ 
tors, Modifying. 98 

Convection of Heat.161, 169 

Conversion of Maltose Type 

Sugars into Glucose. 59 

Converting One Heat Scale Into 

the Other. 80 

'Cooking Starch, Gelatinization. 24 

Com Flakes, Properties of_61 

Cost Calculation Necessary.... 67 
Cutting Over Dough, Effect of. 97 


Dextrin.28, 58 

Description of Microscope.42 

Diastase and Its Functions. 57 

—, Action on Starch. 59 


Differences in Qualities of Malt 
Extract 


Different Temperature, Mixing 

Ingredients of . 86 

Disposal of Infected Flour.120 

Distillers’ Yeast.40, 41 

Distribution of Heat.160 

Dormant Rope, Prevalence of. .121 
Doughs, Adjusting Shop Condi¬ 
tions for . 98 

Dough, Definition.16, 20 

— Fermentation, Objects of.. 95 
-, Effect of Temperature 

on.93 

—, Ideal Temperature for..98, 103 

— Kneading, Rule of Machine. 71 

—, Oxygenation of.55, 97 

—, “Proof” of.146 

— Readiness, How Time is De¬ 

termined . 95 

—, Slack, Bacterial Effect on.. 103 

— Temperature, Calculating 

Water Temperature for.... 89 

— Weighing Machine .143 

—, When at Its Best Condition 93 
Doughing Water, Warmth of.. 75 

— Propensity of Wheat Flour. 16 

Drafts, Chimneys and Chimney¬ 
pots.163 

Dry Yeast. 40 

Education, Fundamental, Im¬ 
portant. 14 

Effect of Over-kneading on 
Bread. 71 

— of Temperature on Fermen¬ 

tation of Dough. 93 

Electric Motors .137 

Underlying Principles.138 

-, Advantage of .137 

Engines, Bakery .128 

—, Gas .128, 129 

Enzymes.58 

Evolution of Bread Recipes.... 72 
Examining Bread, Test Loaves. 180 

— a Ropy Ix)af.119 

Excess of Fermentation in 

Short and Long Methods.. 105 
Experimenting in the Produc¬ 
tion of Rope.108 

Experiments, Value of. 20 

Explosion Motors .128 

External Flue Oven-Principle 

of Continuity.152 

Fahrenheit Temperature Scale. 79 

Fat, Action on Yeast..'... 62 

—as a Moistening Agent... i,.. 62 

— Content of Flour. 34 

— Effect on Fennentation.62 

Fatty Ingredients of Bread.... 62 

Fermentation.50 

—, Acceleration of. 96 

—, Acetic.102 

—, Acid and Putrefactive.107 

—, Butyric.101 


58 

Jago’s Bread-Shop Practice 


188 











































































—, Conditions Affecting Speed 
of.52, 96 

— of Dough, Effect of Temper¬ 

ature on . 93 

—, Effect of Fat on. 62 

—, Excess in Short and Long 
Methods.105 

— Governed by Temperature.. 97 

—, Lactic Acid .101 

—, Modifying Controlling Fac¬ 
tors. 98 

—, Objects of Dough. 95 

—, Retardation of. 97 

—, Sugar Necessary for. 52 

—, Temperature and. 93 

—, Viscous.102 

Filtering Apparatus, Ulus.27 

First Impressions. 15 

— Principles, Wisdom of Mas¬ 

tering. 14 

“Flash” Heat.150 

Flour, Absorption.176,185 

—, Ash in . 30 

—, Baking Pale.180 

— Blending.66, 140 

—, Branny, Most Liable to 

Rope.109 

—, Calculating Specific Heat of 87 

—, Constituents of. 27 

—, Disposal of Infected.120 

—, Fat Content. 34 

— and Fermentation. 97 

—, Hard.16, 17, 18 

—, High-grade Less Liable to 

Rope.110 

—, Miller’s Trial for Ropy.121 

—, Mineral Salts in. 29 

—, Mouldiness and Mustiness. 124 
—, Nature and Properties of.. 16 

— Practically Always Source of 


Rope Infection ... 


...114 

—, Salts in. 

— Sifting. 


19, 20 

_97, 141 

—, Soft. 

..16, 

17, 18 

—, Starch in . 


...20 

—, Strong. 

..16, 

17, 18 

—, Sugars in. 


...29 

—, Testing for Rope.. 


...114 

—, Weak. 

..16, 

17, 18 


it 


Formation of Carbon Dioxide 

Gas.41,51 

Formula and Process, Intimate 

Relation of. 73 

Foxy” Crust.180 

Frontispiece, William Jago.... 2 

Fuels.155 

—, Bakers’.155 

Function of Cane Sugar in 

Bread-Making.60 

-Salt in Bread-Making... 33 

Fundamental Education Im¬ 
portant.14 


Fundamentals, Understanding.. 12 

Gas Engine, The.128 

—, Producer.160 

Gears, Striking.137 

Gelatinized Starch . 24 

General Bakery Machinery.139 

Glucoses. 54 

Gluten, Composition of. 24 

—, Effect of Mineral Salts on. 20 

—, Starch and Minerals. 18 

Good and Bad Radiators and 

Absorbers of Heat.168 

“Handing Up” Loaves.146 

Hard Flour.16, 17, 18 

Heat, Absorbers of.168 

— and Bread-making Opera¬ 

tions. 75 

—, Conduction of.164 

—, Convection of .161 

—, Converting Scales.80 

— Developed During Combus¬ 

tion . . .•.156 

—, Distribution of .160 

—, “Flash”.150 

— has no Weight. 76 

— Measurement, Modes of.... 81 

— Problems of Baking.. .149, 154 

—, Radiation of.159, 165 

—, “Solid”.151 

—, Specific.82 

—, Transmission in Steampipe 

Oven.169 

Hoist, Sack or Barrel.140 

How is Time of Dough Readi¬ 
ness Determined? . 95 

— Rope Develops in an Ordi¬ 

nary Bakery.113 

— Science Helps in Actual Bak¬ 

ery Operations. 68 

— to Use the Microscope.45 

Ideal Dough Temperature. .98,103 
Infected Flour, disposal of.... 120 
Ingredients of Bread, Fatty... 62 

-, Moistening.63 

—, Order of Adding. 70 

— of Different Temperatures, 

Mixing.86 

Intimate Relation of Formula 

and Process. 73 

Introductory. 9 

Invertase. 59 

Investigating Properties of 

Acids. 32 

— Yeast Properties. 41 

Iodine Test for Starch in Yeast 42 

Jago, William.Frontispiece 

Kjieading Machine.143 

— Machines, Modem High 

Speed.72 

—, Machine vs. Hand, in Labo¬ 
ratory Tests.178 

—, Rule of Machine. 71 


Jago’s Bread-Shop Practice 


189 
























































































Knowledge, Applying in Prac¬ 
tice .88 

Laboratory, The Bakery.173 

— Apparatus Required ...173, 183 

— Baking, Quantities Used for.176 

— Formula.175 

— Kneading, Machine vs. Hand.178 
—, Position and Fittings of... .173 

— Tests.174, 184 

— Working Temperatures ....176 

Lactic Acid .106 

— Acid Fermentation.101 

— Acid Produced During Fer¬ 

mentation .105 

Litmus.31, 49 

Long Methods, Excess of Fer¬ 
mentation .105 

Machinery, Bakeshop.127 

— Alleviates Hard Work. 69 

Machine, Dough Weighing.143 

—, Kneading.143 

— Dough Kneading, Rule of.. . 71 

— vs. Hand Kneading in Labo¬ 

ratory Tests.178 

— Mixing, Changes Required 

for.69 

—, Moulding.144 

—, Sifting.141 

Make the Ambitious Choice.... 10 
Making Baking Tests. 67 

— Laboratory Baking Tests.. .174 

Malt Products, Bakery. 57 

— Extract.57, 58, 61 

Maltose.29, 54, 58 

Marks, Bakers’ Scoring.181 

Materials, Bakers’ Raw. 16 

Materials Other Than Flour, 

Valuation of.182 

Measurement of Heat, Modes of 81 
Measuring, Accuracy Essential. 141 

— and Attemperating Water.. 141 
Mechanical Bakery Appliances. 127 

Microscope, Description of.42 

—, How to Use. 45 

—, Illustration.44 

—, Under the. 42 

Microscopic Examination of 

Yeast.47 

Milk as a Moistening Agent... 63 
—, Composition of Cow’s. 63 

— Powder. 64 

Miller, Precautions for.117 

Mineral Nutriment Required by 
Yeast.55 

— Salts, Effect on Gluten.20 

—Salts in Flour. 29 

Minerals, Starch and Gluten... 18 

Mixing Ingredients of Different 

Temperatures.86 

—, Changes Required for Ma¬ 
chine . 69 


Modern High Speed. Kneading 

Machines.72 

Modes of Blending Flour.68 

Modifying Controlling Fermen¬ 
tation Factors. 98 

Moistening Agent, Milk as a.. 63 

— Ingredients of Bread.63 

• — Properties of Fat. 62 

Moisture in Bread.151 

— in Rope Development..... .116 
Motors, Advantages of Electric.137 

—, Electric.137 

—, Explosion.128 

—, “Four Cycle” System.128 

—, Underlying Principles.138 

Mouldiness and Mustiness.124 

Moulding.146 

— and Its Nature.144 

—Machines. 144 

Mustiness and Mouldiness.124 

Nature of Yeast. 37 

— and Properties of Flour.... 16 

Nitrogenous Matter. 49 

Normal Salt.. • • 32 

Objects of Dough Fermentation 95 

Operation of Baking.149 

Operations, Bread-Making .... 66 
Order of Adding Ingredients.. 70 
Origin and Production of Yeast 39 

Oven, Continuous.152 

—, External Flue.152 

—, Side-flue.150 

— Steampipe.153,169 

— Types, Primitive .149 

Over-kneading, Effect on Bread 71 

Over-mixing, Avoid. 71 

Oxygen, Yeast AflEinity for Free 55 

Oxygenation of Dough.55, 97 

-Yeast. 55 

“Patent” Yeast. 40 

Peel, Bread.150 

Position and Fittings of Labo¬ 
ratory .173 

Potassium Phosphate .30, 55 

Potato as Source of Rope.110 

—, Composition of Dried.61 

—, Cooked, Properties of. 61 

—, Effect on Fermentation of.. 97 

Powder, Milk. 64 

Power, Bakery Sources of..... 127 

— Absorbed by Running Gear. 137 

—, The “Four Cycle” System.. 128 
—, The Gas Engine.128 

— Requirements, Bakery.128 

Practical Proving Cupboard, 

Laboratory.178 

Practice, Applying Knowledge in 88 

— and Science. 12 

Precautions for the Miller.117 

Prevalence of Rope.118 

Prevention of Rope.118 

Primitive Oven Types.149 


190 


Jago*s Bread-Shop Practice 




















































































/ 


Problems of Baking*, Heat.149 

Process and Formula, Intimate 

Relation of. 73 

Producer Gas.160 

Production of Alcohol. 52 

Progress of Knowledge Regard¬ 
ing Action of Yeast. 39 

“ProoP’ of Dough.146 

Proving or Proofing Cupboard, 

Laboratory.179 

Proper Characteristics of Com¬ 
pressed Yeast. 41 

I'roperties of Acids. 32 

-Com Flakes and Cooked 

Potato.61 

Publishers’ Preface . 5 

Pulleys.131 

—, Size of.134 

Putrefaction, Organism of.101 

Pyrometer, The.170 

Quantity of Heat, Modes of 

Measurement.81 

Quantities Used for Laboratory 

Baking.176 

Radiation of Heat.157,165 

Radiators of Heat, Good and 

Bad.168 

Readiness of Dough. 95 

Recipes, Evolution of Bread... 72 
Regular System of Rope Tests. 118 
Remarkable Growth of Yeast.. 51 

Researches, Watkins’s.113 

Retardation of F'emientation... 97 

Rope in Bread.102, 108 

—, Baker’s Risk .121 

—, Flours Most Liable to.109 

—, Causes of.108, 110 

— Development, Acidity Inim¬ 

ical to.Ill, 113, 120 

— Development, Moisture in... 116 
—, Elfect of Temperature on.. 113 

—, Examining Bread for.119 

—, Experimenting in the Pro¬ 
duction of .. 108 

—, How it Develops in an Ordi¬ 
nary Bakery.113 

— Infection, Flour Practically 

Always Source.114 

— Inhibited by Acetic Acid.113,120 

—, Miller’s Trial for Responsi¬ 
bility .121 

—, Potatoes as Source of.110 

—, Precautions for Miller.117 

—, Prevalance of Dormant... .121 
—, Prevention of .118 

— Tests, Regular System of.. .118 

—, Testing Flour for.114 

Rule of Machine Dough Knead¬ 
ing. 71 

Saccharine Extracts, Effect on 
Fermentation of. 97 


Sack or Barrel Hoist.140 

Salts. 30 

—, Acid and Normal.31, 32 

—, Common.33 

— in Flour.19, 20, 29 

—, Functions in Bread-making 33 

—, Mineral, in Flour. 29 

— a Retarding Agent in Fer¬ 

mentation .97 


— and Yeast, Mixing in Dough 69 

Scales, Converting Heat. 80 

Schizomycetes, The.100 

Science and Practice. 12 

— Helps in Bakery Operations 68 

Scoring Bread.181 

Self-reliance, Value of. 11 

Separation, Analysis. 21 

Shafting.130 

Shortening. 62 

Short Methods, Watching Time 

in.105 

Side-flue Oven.150 

Sifting Flour.97, 141 

— Machines.•.141 

Size of Pulleys.134 

Slack Doughs and Temperature, 

Bacterial Effect on.103 

Soft Flour.16, 17, 18 

“Solid” Heat.151 

Soluble Starch. 28 

Sour Bread, Causes of... .103, 107 

— — as Understood by the 

Baker.100 

Sourness. 31 

Specific Heat. 82 

-of Flour, Calculating.... 87 

Speed of Fermentation, Condi¬ 
tions Affecting. 96 

Starch, Composition of. 24 

—, Cooking (Gelatinization) . . 24 

— and Gluten. 24 

— in Flour. 20 

— in Yeast. 41 

—, Iodine Test for. 42 

—, Microscopic Sketches of. .. . 25 

—, Minerals and Gluten. 18 

—, Soluble.28 

—, What Examination Shows.. 24 
Steam in Furnace.159 

— Pipe Ovens.153 


-, Transmission of Heat 


in.169 

Sterilizing and Cleaning of Bak¬ 
ery, Why Advocated.117 

Straight Dough, Mixing a. 69 

Striking Gears.137 

Strong Flour.16, 17, 18 

Studying Consumer Demand... 66 

Sucrose (see Sugar, Cane 

Sugar). 55 


Jago’s Bread-Shop Practice 


191 


I 


















































































Sugar in Bread-making. 

52, 54, 60. 97 

—, Double Function in Fermen¬ 
tation .54 

—, Effect on Fermentation.... 97 

— in Flour. 29 

— Necessary for Fermentation 52 

Sugars. 54 

—, Composition and Chemical 

Changes.54 

Summary... .End of Each Chapter 

Synthesis, Building Up. 21 

System of Graduating Ther¬ 
mometers . 78 

Systematic Cleansing of Bakery.119 
Tank, Water Measuring and 

Attemperating.141 

Taking Dough, Best Time for.. 93 
Temperature, Allow for Cooling 

Effect of Troughs, etc.84 

—, Calculating Water for Dough 

Temperature.89 

—, Effect of on Fermentation 

of Dough. 93 

—, Effect on Rope.113 

— Experiments.52 

— and Fermentation. 93 

— Governs Fermentation. 97 

—, Ideal for Dough.98, 103 

—, Laboratory Working.176 

— Lost Through Contact with 

Machines.85 

— and Slack Doughs, Bacterial 

Effect on.103 

— the Measure of Warmth.... 76 

— Scales. 78 

Tests, Apparatus for.184 

—, Flour Absorption.176 

—, Laboratory.174, 184 

—, Laboratory Baking.174 

—, Making Baking. 67 

—, Rope, System of.118 

Testing Flour for Rope.114 

Thennometers, Action of Oven. 170 
—, Ingenious Baker’s . 89 

— Required for Accuracy. 76 

—System of Graduating. 78 

Time Serious in Short Methods. 105 
—, Watching in Short System. 105 
Transmission of Heat in Steam- 

pipe Oven.169 

Troubles, Bacterial Bread-mak¬ 
ing .100 

Under the Microscope. 42 

Underlying Principles of Elec¬ 
tric Motors.138 

Understanding Fundamentals.. 12 

Valuation of Materials Other 
Than Flour.182 


Value of Experiments, 


20 


Viscous Fermentation .........102 

Volume of Dough Indicates 

Readiness.95 

Warmth of Doughing Water... 75 
—, Temperature the Measure of 76 

Water Absorption Tests...176 

—, Accurate Measuring and 
Temperature Essential .... 141 

—, Doughing, Warmth of. 75 

—, Effect on Fermentation.... 97 
—, Measuring and Attemperat¬ 
ing Tank.142 

— Scale.142 

— Supply for Baker.. 63 

— Temperature, Calculating for 

Dough Temperature.89 

Watkins’s Researches.113 

Weak Flour.16, 17, 18 

Weighing, Accuracy Essential.. 141 

— Machine, Dough.143 

Weight, Heat Has No. 76 

What Chemistry Teaches.20 

— Starch Examination Shows. 24 

Wheat Flour, Doughing Pro¬ 
pensity.16 

— Starch. 18 

When Dough is at Its Best 

Condition.93 

Why Bakery Cleaning and Ster¬ 
ilizing are Advocated.117 

Wisdom of Mastering First 

Principles. 14 

Working Temperatures, Labo¬ 
ratory .176 

Wort. 58 

Yeast. 96 

—, Accelerating Fermentation. 96 
—, Action of. 39 

— Affinity for Free Oxygen... 55 

—, Capabilities of. 49 

— Cells, Colonies. 51 

—, Composition of. 48 

—, CompressecJ, Proper Charac¬ 
teristics .41 

—, Effect of Fat on. 62 

—, Growth of. 50 

—, History of Origin. 40 

—, Mineral Nutriment Required 
by. 55 

— and Its Nature. 37 

—, Origin and Production. 39 

—, Oxygenation of.55, 97 

— Properties, Investigating ... 41 

^—, Remarkable Growth of. 51 

— and Salt, Mixing in Dough. 69 

— Structure.48 

—, Starch in. 41 

-, Iodine Test for. 42 

— Under the Microscope.47, 51, 52 

— a Wasteful Feeder. 53 

Zymase, Action of. 60 


192 


Jago's Bread-Shop Practice 










































































































































































